LIBRARY OF CONGRESS, 



€fjap Gfljp ymn t Ipr; 

L2££/ 

UNITED STATES OF AMERICA. 



SPECTACLES 



EYEGLASSES 



THEIR FORMS MOUNTING AND 
PROPER ADJUSTMENT 



BY 

R. J. PHILLIPS, M.D., 

INSTRUCTOR IN DISEASES OF THE EYE, PHILADELPHIA POLYCLINIC AND COLLEGE 

FOR GRADUATES IN MEDICINE ; OPHTHALMIC SURGEON TO THE 

PRESBYTERIAN HOSPITAL IN PHILADELPHIA. ETC. 



WITH 47 ILL USTRA TIONS. 




( 

V 

PHILADELPHIA: / ?fe$~^ 

P. BLAKISTON, SON & CO., 

JOI2 WALNUT STREET. 

3892, 






Copyright, 1892, by P. Blakiston, Son & Co. 



Press of Wm. F. Fell & Co., 
1220-24 Sansom St., 

PHILADELPHIA. 



PREFACE. 



This little work is the outgrowth of the instruction on 
the subject of prescribing spectacle frames which has been 
given to successive classes at the Philadelphia Polyclinic 
and College for Graduates in Medicine. The book, like 
the teaching referred to, is intended to supplement studies 
in refraction, and to give the student that knowledge of 
the correct placing of the glasses before the eyes without 
which the most painstaking measurement of the refraction 
will frequently fail of practical result. With the populari- 
zation, as one may call it, of ophthalmology in the pro- 
fession, many physicians who prescribe glasses are com- 
pelled, by the lack of skilled opticians in their neighborhood, 
to themselves furnish the spectacles to the patient. To 
these, it is believed, the knowledge which I have endeavored 
to impart in these pages will prove especially useful. 

Of late years much advance has been made in the art of 
making efficient, comfortable and handsome contrivances 
for holding glasses before the eyes, and the increased use 
of prismatic and cylindrical lenses has given the fitting of 
the frames increased importance. Text-books of refraction 
remain, however, almost devoid of reference to the subject, 
the scant literature of which is scattered through opticians' 

iii 



IV PREFACE. 

trade publications, and a few medical periodicals. Free 
application has been made to such sources, and the in- 
debtedness incurred duly acknowledged in the text. 

My thanks are due to my friend and instructor, Dr. 
Edward Jackson, for many valuable suggestions in writing 
this treatise, and, indeed, for directing my attention to the 
need of a book on spectacles. 

Dr. George M. Gould kindly furnished me with some 
references used in the introduction, and I am indebted to 
The Philadelphia Optical and Watch Co., and to Messrs. 
Wall & Ochs, for a number of cuts. 

March, i8q2. 



CONTENTS. 



PAGE 

Introduction, 17 

I. General Considerations, 26 

The Material of Frames, 26 

The Component Parts of Spectacles, 27 

The Lenses : Their Material and Manufacture, 28 

Eye Wires, Temples, and Bridges, 34 

The Different Patterns of Spectacles, ... 34 

The Varieties of Eyeglasses, 40 

Spectacles for Cosmetic Effect, 43 

II. The Principles of Spectacle Fitting, 44 

Centering and Decentering, 44 

Prismatic Effect of Decentering, 46 

Normal Lateral Centering, 49 

Normal Vertical Centering, 50 

Distance of the Glasses from the Eyes, 51 

Perpendicularity of the Plane of the Lenses to the Visual Axes, . 52 

Periscopic Glasses, 56 

III. Prescription of Frames, 59 

The Measurements Required, 59 

Obtaining the Interpupillary Distance, 61 

Height of the Bridge, 65 

Relation of the Top of the Bridge to the Plane of the Lenses, . . 66 

Width of Base, 67 

Prescription of Eyeglasses, 69 

IV. Inspection and Adjustment of Spectacles and Eyeglasses, 70 

Proving the Strength of Lenses, 70 

Phacometers, 71 

Neutralization of Spherical Lenses, 73 

Neutralization of Cylindrical Lenses, ..,...,,,.,. 74 

V 



VI CONTENTS. 

Inspection and Adjustment of Eyeglasses, Etc. — Continued. PAGE 

Neutralization of Sphero-cylindrical Lenses, ....-*. . 75 

Locating the Optical Center, 76 

Finding the Apex of a Prism, 77 

Measuring the Strength of a Prism, 77 

Detection of Scratches, Specks, Flaws, Etc., 82 

Irregularity of the Refracting Surfaces, . 83 

Adjusting Spectacle Frames, S3 

Adjustment of Eyeglasses, 89 

The Care of Spectacles, 92 



LIST OF ILLUSTRATIONS. 



FIGURE PAGE 

1. Position of the parts of spectacles, 28 

2. Position of the parts of eyeglasses, 28 

3. Optician's lens-grinding lathe, 30 

4. Concave toric and concave cylindrical lens, ^^ 

5. Frameless bifocal spectacles, 35 

6. Forms of spectacle bridges, 36 

7. Ovals, showing the sizes of spectacle eyes, 38 

8. Forms of bifocal glasses, 39 

9. Extra front, 41 

10. Forms of rigid frame eyeglasses, 41 

11. Modern frameless eyeglasses, 42 

12. Spectacles with lenses decentered " in," 45 

13. Section of a normally centered lens, 47 

14. Decentered lens, showing prismatic effect, 47 

15. Profile view of the face, showing the "natural" position for the 

spectacle bridge, 51 

16. Top of bridge " out " from plane of the lenses, 52 

17. Top of bridge "in" from plane of the lenses, 52 

18. Spectacles facing directly forward, 54 

19. Spectacles facing downward and forward, 54 

20. Spectacles facing inward, 55 

21. Front and back of a convenient spectacle rule, 60 

22. Method of measuring the height of a spectacle bridge, 62 

23. Simplest method of measuring the interpupillary distance, 62 

24. Maddox pupil localizer, 63 

25. Method of using the Maddox pupil localizer, 63 

26. Meyrowitz pupilometer, 64 

27. A common form of pupilometer, 6$ 

28. Method of measuring the distance of the bridge " out," 66 

29. Method of measuring the distance of the bridge " in," 67 

30. Mr. Brayton's lens measure, 72 

31. Apparent displacement of lines caused by rotating a cylinder, ... 74 

vii 



Vlll LIST OF ILLUSTRATIONS. 

FIGURE PAGE 

32. Method of finding the axis of a cylindrical lens, 74 

33. Ready method of locating the optical center of a lens, 76 

34. Mode of marking the apex of a prism, 77 

35. A prism improperly held, 77 

36. Implement for measuring the refracting angle of prisms, 80 

^J. Method of determining the deviating angle of prisms, 81 

^8. Rotation of a lens within its eyewire, 83 

39. Bend at the junction of the eyewire and bridge, 84 

40. Showing the planes of the lenses crossing each other, 84 

41. Bend of the bridge, 85 

42. Inequality of corresponding angles of the bridge, 85 

43. Angles on one side of the bridge too small; on the other too large, . 85 

44. Proper fitting of hook temples, 88 

45. A common but incorrect shape of the nose pieces of eyeglasses, . . 89 

46. Eyeglasses with nose pieces of correct shape, 90 

47. The points at which eyeglasses are to be adjusted, 91 



SPECTACLES AND EYEGLASSES. 



INTRODUCTION. 

At what time man invented lenses and discovered the 
aid which they are capable of lending to vision is a matter 
beyond our knowledge. It is tolerably certain that they 
were known to civilizations earlier than ours. The late 
Wendell Phillips was wont to assert that spectacles were 
among the things known to the ancients. Though it 
might be difficult to sustain this assertion as regards spec- 
tacles in the present meaning of the term, the evidence in 
relation to their acquaintance with the essential element of 
spectacles, the lens, is reasonably convincing. This evi- 
dence was for the most part discovered by Sir Austen 
Henry Layard, among the ruins of old Nineveh, and is of 
the most interesting character. Among the articles which 
he unearthed, was a specimen of transparent glass (a small 
vase or bowl) with a cuneiform inscription fixing its date 
quite accurately to the latter part of the seventh century 
B. C. (" Discoveries Among the Ruins of Nineveh and 
Babylon, etc.," by Austen H. Layard, New York, 1853, p. 
196.) This is the most ancient known specimen of trans- 
parent glass, though Egypt furnishes it of a date only a 
century later, and opaque or colored glass was manufac- 
tured at a much earlier period; some specimens of the 
fifteenth century B. C. still enduring. However, the ancient 
nations were not compelled to wait for transparent glass 
2 l 7 



1 8 SPECTACLES AND EYEGLASSES. 

in order to invent lenses, as they had in rock crystal a 
material admirably adapted to that purpose, and Layard 
was so fortunate as to discover such a lens in Nineveh. 
{Ibid. p. 197). Sir David Brewster, who examined this 
lens, described it as being plano-convex, of a diameter of 
one and a half inches, and capable of forming a tolerably 
distinct focus at a distance of four and a half inches from 
the plane side. It is interesting to note farther in regard 
to this, the oldest lens in existence, that it is fairly well 
polished, though somewhat uneven from the mode in which 
it was ground, which Brewster concludes was not upon a 
spherical surface, but by means of a lapidary's wheel, or 
some method equally rude. Another evidence of the use 
of lenses has come down to us from antiquity. Upon 
record-cylinders of old Nineveh, and on engraved gems 
and stones of Babylon, Egypt, and other sources which 
long antedate the Christian era, are characters and lines of 
such delicacy and minuteness as to be undecipherable 
without the aid of a magnifying lens. Taking these facts 
in conjunction, the statement that some of the properties 
of lenses were known to and utilized by the ancients, the 
old record writers of Assyria, for instance, may be regarded 
as almost as well demonstrated as though it were made 
of a modern engraver, and we were to step into his work- 
shop and find his magnifying loup lying beside his work. 

The testimony as to their use by the Romans during 
their supremacy is of a less conclusive character. The 
statement frequently made that the Emperor Nero used a 
concave jewel to assist his sight rests upon some obscure 
sentences in Pliny. That author says : " Nero could see 
nothing distinctly without winking and having it brought 
close to his eyes." (Bk. 11, Chap. 54, Riley's Trans.) 
In another place, speaking of the emerald, smaragdiis, he 



INTRODUCTION. 1 9 

says : " In form these are mostly concave, so as to reunite 
the rays of light and the powers of vision. * * * 
When the surface of the smaragdus is flat, it reflects the 
image of objects in the same manner as a mirror. The 
Emperor Nero used to view the combats of gladiators upon 
(with, or by means of) a smaragdus." (Bk. 37, Chap. 17.) 
The mention of the reflecting properties of the emerald 
immediately before the statement of Nero's use of it, with 
the alternative renderings of the Latin ablative, smaragdo, 
make the supposition that Nero used the emerald as an 
eyeglass uncertain, though in view of his clearly described 
nearsightedness, the conjecture is probable enough. 

Lenses appear to have been unknown in Europe during 
the first twelve hundred years of the Christian era, though 
the Saracen Alhazen, who died in Cairo in 1038, has left 
books showing his acquaintance with them. These books 
were brought to Europe at a very early period, and the 
manuscripts yet exist ; some in the Bodleyan library, and 
another portion in that of the University of Leyden. It 
was probably from them that the early writers obtained 
their first hints of the science of optics, on the revival of 
learning in the fourteenth and fifteenth centuries. It is 
worthy of note that Alhazen was born at Bassora, at the 
head of the Persian Gulf, and less than five hundred miles 
from the spot where, sixteen hundred years before, had 
stood the palace of the Assyrian kings in the ruins of 
which Sir Henry Layard found the lens of crystal. It 
might, perhaps, be plausibly maintained that in the countries 
about the Tigris some knowledge of optics, and of convex 
/lenses, has persisted without eclipse from the most remote 
ages. 

The earliest European reference to our subject occurs in 
the writings of Roger Bacon, who died in 1292, and to 



20 SPECTACLES AND EYEGLASSES. 

whom the invention of the instrument he describes is 
sometimes accredited. Bacon's glass was apparently a 
large plano-convex lens, probably what we now call a 
reading glass, intended to be held in the hand, and of it 
he says : " This instrument is useful to old men and to 
those that have weak eyes ; for they may see the smallest 
letters sufficiently magnified." Spectacles proper ; that is, 
glasses mounted so as to retain themselves upon the face, 
appear to have been invented in Florence somewhere 
between 1280 and the close of the thirteenth century. 
Dr. Samuel Johnson is said to have expressed surprise that 
the inventor of such useful articles has found no biographer. 
Doubtless among the thousands for whom the discovery 
has kept open the sources of knowledge there would be 
found one to pay this tribute to the fame of his benefactor 
were the identity of the latter a matter of certainty. But, 
unfortunately, our evidence on the point is of the most 
fragmentary character. We are told in a general way that 
the Chinese have for ages employed spectacles for the relief 
of defective eyesight. This is, perhaps, to be regarded as 
only another instance of the exercise of that claim to 
priority which the Chinese are known to extend over every 
good and perfect gift. The longest chase signally fails to 
bring the tradition to bay in any fact. The tomb of Salvinus 
Armatus, a Florentine nobleman who died in 13 17, is said 
to bear an inscription to the effect that he was the inventor. 
If epitaphs enjoyed a less equivocal reputation for truthful- 
ness he would doubtless be held in grateful remembrance 
as the man who has lengthened youth by postponing old 
age ; and, like Joshua, kept back the night until the day's 
work was done. 

Whoever the inventor, Alessandro di Spina, a monk of 
Florence who died in 13 13, is generally accredited with 



INTRODUCTION. 21 

having made public the use of spectacles, and by several 
Florentine writers of that time we find them mentioned 
and recommended. Pissazzo, in a manuscript written in 
1299, sa y s : "I fi n d myself so pressed by age that I can 
neither read nor write without those glasses they call 
spectacles, lately invented, to the great advantage of poor 
old men when their sight grows weak." Friar Jordan, of 
Pisa, in 1305 says that " it is not tw r enty years since the art 
of making spectacles was found out, and is indeed one of 
the best and most necessary inventions in the world." 

An early mention of spectacles, or in the language of 
that time, " a spectacle," occurs in " The Canterbury Tales," 
where Chaucer makes the Wife of Bath use the metaphor : — 

Povert (poverty) full often when a man is lowe, 
Makith him his God and eek himself to knowe. 
Povert a spectacle is, as thinkith me, 
Through which he may his verray frendes se. 

There is in existence in the church of Ogni Santi, 
Florence, an old fresco by Domenico Ghirlandajo, repre- 
senting St. Jerome, and dated 1480. The saint is portrayed 
seated at a desk, apparently deep in the composition of one 
of the blasts against the Heretics for which he was famous. 
Upon a peg at the side of the desk, together with the ink 
horn and a pair of scissors, hangs a small handleless pince- 
nez. The glasses are round and framed in dark bone, and 
in the bridge, also of bone, is a hinge. Though the artist 
seems to have been little impressed by the fact that St. 
Jerome died in the year 420, nearly nine centuries before 
spectacles were invented, the mounting and material repre- 
sented in these early spectacles are worthy of note as 
showing their form in Ghirlandajo's time, and probably 
that in which they originated. 

In the early references to spectacles it is the convex lens 



22 SPECTACLES AND EYEGLASSES. 

for the use of the presbyopic which is mentioned. Concave 
lenses were probably introduced soon afterward ; by whom 
we do not know. Glasses were at that time a'nd for long 
afterward selected and used empirically ; since it was not 
until the year 1600 that the astronomer, Johann Kepler, 
who may be regarded as the father of ophthalmology, made 
known in what manner the rays of light were refracted by 
the media of the eye and form an image upon the retina. 
Kepler went farther, and showed how convex and concave 
glasses influence this refraction, and to him is therefore 
due the honor of first scientifically treating this subject. 

It must have been early discovered that there is a more 
or less close relation between the age of the wearer and 
the strength of the convex glass required, and the baneful 
theory was soon developed that this relation is constant, 
and that it would be ruinous to use a lens " too old for the 
eyes ; " a superstition from which the public is even yet not 
fully emancipated. We find it rampant in Pepys' time, 
preventing his oculist, Dr. Turberville,* from giving that 
gentleman a proper correction for his accommodative 
asthenopia, of which the diary gives an accurate picture, 
and losing to the world many a priceless page. Pepys 
says (June 30, 1668): u My eyes bad, but not worse, only 
weary with working. * * * I am come that I am not 
able to read out a small letter, and yet my sight good, for 
the little while I can read, as ever it was, I think." But 
Dr. Turberville warns him against glasses too old for him, 
and so the diary is closed, and Pepys in a last pathetic 
entry resigns himself to coming blindness ; and yet the 



* Daubigny Turberville ; created M.D. at Oxford in 1660. He practiced 
with great reputation as an oculist in London. His monument yet remains in 
Salisbury Cathedral, where he was buried. 



INTRODUCTION. 23 

convex lenses were at his hand, ready to dissipate the mists 
before him and enable him to " gaze upon a renovated 
world." 

Improvement in spectacles appears to have been slow. 
The world waited more than two centuries after Kepler 
for another signal advance. Sir David Brewster is said to 
have discovered his own astigmatism ; that is, he discov- 
ered that vertical and horizontal lines were not equally 
well seen by him at like distances, but the phenomenon 
was not explained and the observation faded from view. 
It remained for George Airy, the astronomer, to rediscover 
astigmatism, which he did about 1827, to determine that 
the curvature of the cornea was greater in one diameter 
than in another at right angles to the first, and to invent 
the cylindrical lens for the correction of the condition. Mr. 
Airy's right eye was myopic, while in the left he had com- 
pound myopic astigmatism. By a careful comparison of 
the appearance of objects when viewed with each eye 
singly, and a study of the effect of concave lenses held 
before the left eye upon lines crossing each other at right 
angles, he was able to conclude that the refraction of that 
eye differed in different planes. Mr. Fuller, an optician of 
Ipswich, made, under Airy's direction, a concave sphero- 
cylindrical lens which satisfactorily corrected his refractive 
error. Thus was the last great discovery in spectacles 
accomplished ; a bit of work for completeness leaving 
nothing to be desired, and of not sufficiently acknowledged 
importance to humanity. 

Benjamin Franklin invented bifocal spectacles. Since 
this statement is supposed by many to rest on tradition 
'only, it may be of interest to quote a portion of a letter of 
Franklin's which bears upon the point. The letter is ad- 
dressed to George Whately, of London, and is dated 



24 SPECTACLES AND EYEGLASSES. 

Passy, 23d May, 1785. In it Dr. Franklin says: " By Mr. 
Dolland's saying that my double spectacles can only serve 
particular eyes, I doubt he has not been rightly informed 
of their construction. I imagine it will be found pretty 
generally true that the same convexity of glass through 
which a man sees clearest and best at the distance proper 
for reading, is not the best for greater distances. I there- 
fore had formerly two pairs of spectacles which I shifted 
occasionally, as in traveling I sometimes read, and often 
wanted to regard the prospects. Finding this change 
troublesome and not always sufficiently ready, I had the 
glasses cut and half of each kind associated in the same 
circle. By this means, as I wear my spectacles constantly, 
I have only to move my eyes up or down, as I want to see 
distinctly far or near, the proper glasses being always 
ready. This I find more particularly convenient since my 
being in France. * * *" (" The Complete Works of 
Benjamin Franklin." Ed. by John Bigelow, New York, 
1888.) 

We may infer from the context that the invention took 
place before Franklin went to France, which was in the 
latter part of 1776. As he was born in 1706, the necessity 
for a double glass would first arise about 1750, and the 
invention therefore took place somewhere between this 
date and that of the journey to France. 

The frames in which spectacles were mounted continued 
to be very clumsy affairs until the beginning of this cen- 
tury, when Tight metal frames were introduced in place of 
the earlier devices of bone, horn, or shell. Their later 
evolution has generally been along the lines of improved 
mechanical construction, and increased lightness and beauty. 
It would be difficult to mention an article which plays a 
more important part in modern life than do spectacles, or 



INTRODUCTION. 25 

one which plays its part more acceptably. It is scarcely 
possible to estimate them at their true worth, or to imagine 
our condition without them. Deprived of their aid, most 
men would be too old for work at fifty, and purblind at 
sixty. For us all, as an old writer quaintly observes, 
" they keep the curtain from falling until the play has come 
to an end." 



I. GENERAL CONSIDERATIONS. 

By far the most generally useful method of placing 
glasses before the eyes is by spectacle frames, though the 
eyeglass, or pince-nez, has advantages in some cases, from 
the facility and quickness with which it may be placed in 
position or removed. The superiority of eyeglasses in 
appearance and becomingness is another point not unworthy 
of consideration, as the glasses will surely be more con- 
stantly worn if they are becoming than if they are not so. 
Moreover, the patient is justly entitled to the correction of 
his refractive error with as little injury to his appearance as 
possible. The disadvantages of eyeglasses are, that for 
constant wear they are seldom so comfortable as spectacles ; 
that on some faces it is nearly impossible to keep them in 
place ; while, where the contained glass is cylindrical or 
prismatic, the rotary motion which it is possible for the 
glass to take is a serious, and sometimes fatal objection to 
their adoption. 

Lorgnettes and single eyeglasses, or quizzing glasses, as 
they are called, are little more than playthings ; though 
sometimes, as in aphakia, or high myopia, a strong convex 
or concave lens in one of these forms is of use when the 
spectacles constantly worn do not give the vision which 
may occasionally be required. 

The material of spectacle frames is usually gold, silver, 
or steel. Various alloys have also been employed, and 
sold as aluminium, or nickel. So far as I have examined 
them, they consist principally of tin, and contain little or 

26 



GENERAL CONSIDERATIONS. 2J 

none of the metals whose names they borrow. Real nickel 
is too flexible a metal to be used with advantage for spec- 
tacle frames, while, so far, no means have been found of 
soldering aluminium firmly. Were this difficulty overcome, 
the lightness, stiffness and freedom from rust of aluminium 
would make it an excellent material for cheap frames. 
Silver, like nickel, is too flexible, except for workmen's 
protective goggles, or some such purpose, where very 
heavy frames are allowable. Gold, of from 10 to 14 karat, 
is, by far, the best material for frames. Finer than this it is 
too flexible, while if less pure it may blacken the skin. In 
the end, such frames are cheaper than steel, as, owing to 
the liability of the latter metal to rust when in contact with 
the moist skin, the gold will outlast it many times over. 
In eyeglasses, however, the parts are heavier, and the metal 
is not in contact with the skin ; so that there is not the 
same liability to rust. The gold frames furnished by opti- 
cians in this country usually have a stamp mark on the 
inner side of the right temple, near the hinge, which denotes 
the fineness of the gold: thus 8 karat is marked + ; 10 
karat, 6; 12 karat, *; while 14 karat, or finer, is marked 
14k, etc. 

The Component Parts of Spectacles. — A pair of 
spectacles is made up of fifteen or seventeen pieces, whose 
positions are shown in Fig. I. They are : two lenses, two 
eye wires, four end pieces, two screws, two pins, or dow r els, 
two temples and one bridge. Sometimes the rings upon 
the temples, through which the dowels pass, are formed as 
separate pieces. Fig. 2 shows the name and position of 
each part of an eyeglass. A glance at the more important 
of the many interesting processes required in making these 
different parts will contribute to an understanding of the 
subject. 



28 



SPECTACLES AND EYEGLASSES. 



I 



The Lenses.— The word lens is the Latin name of the 
lentil, a small bean. The resemblance in shape caused the 



Fig. i. 





name to be applied to the optical implement. Spectacle 
lenses are usually made of glass; sometimes of rock 



GENERAL CONSIDERATIONS. 29 

• 

crystal (crystallized quartz). The latter substance has a 
slightly higher index of refraction, so that a lens of a given 
strength may be somewhat lighter when made of it than 
when made of glass. The notion is common that these 
" pebbles," as they are called, possess a peculiar virtue in 
strengthening the eyes, or in some other direction. I sup- 
pose the idea is, that being the product of Nature's labora- 
tory, they are necessarily superior. The advantage which 
they may have of being slightly lighter and harder than 
lenses of glass, is more than counterbalanced by their 
higher cost, and by the fact that the index of refraction of 
rock crystal is not very constant. 

Of the different kinds of glass, that known as crown 
glass is preferred, on account of the superior brilliancy 
which it possesses. It differs from ordinary sheet glass 
only in the method of blowing. At one point in the pro- 
cess, the mass of glass on the blowpipe assumes the shape 
of a crown ; hence the name. Although glass is theoreti- 
cally a definite chemical compound, the different methods 
of handling make a considerable difference in the product 
of different makers. It consists, chemically, of silicic acid 
united with some two of the metallic bases : sodium, 
potassium, calcium, magnesium, aluminium, iron and lead, 
but owing to impurities in the glassmaker's raw materials, 
traces of several more of these bases are generally present. 
The bases calcium and soda are those used for ordinary 
sheet and crown glass ; iron, always present as an impurity, 
giving the product its greenish tinge. To lessen this tint, 
arsenic is employed as a bleaching agent. Peroxide of 
manganese is sometimes used for the same purpose, and it 
is a slight excess of this agent which gives to certain 
samples of glass their pinkish tint. The transparency of 



30 



SPECTACLES AND EYEGLASSES. 



such glass is thought to be less durable than that having 
the greenish color. 

The simple apparatus used for grinding a single spherical 
lens is shown in Fig. 3. The disc of glass (a) of which a 
lens is to be made is fastened, by means of pitch, to a small, 
cubical block of iron (b) having a pit in the surface oppo- 
site that to which the glass is fastened. Into this pit fits .a 



Fig. 3. 




Optician's Lathe, for Grinding Spherical Lenses. 



pin (V) upon a lever which is in the hand of the workman. 
When the free surface of the glass is applied to the surface 
of the " tool," (d) to whose form it is to be ground, it, 
together with the block of iron, turns upon the pin. The 
joints at e and/ allow of lateral and vertical movements of 
the lever, so that the workman is able to carry the glass 
freely over all portions of the tool. 



GENERAL CONSIDERATIONS. 3 I 

The tool which gives the shape to the surface of the 
glass is made of steel ; and for spherical glasses is in the 
form of a disc, with its surfaces looking upward and down- 
ward, and revolving about a vertical axis, like a potter's 
wheel. The upper surface of this disc is convex for grind- 
ing concave glasses, or concave for grinding convex 
glasses. Of course each strength of lens requires a 
separate tool having the requisite convexity or concavity 
of surface. The abradmg material placed upon the 
surface of the tool is wet powdered emery, of succes- 
sively finer and finer grades until the desired amount of 
glass has been ground away. When this process is com- 
plete, the surface of the glass has the desired spherical 
curvature but it is rough : that is, it is " ground glass." To 
polish it a piece of wet broadcloth or felt is smoothly 
applied to the surface of the tool upon which the glass was 
ground, conforming, of course, to that surface. The cloth 
being sprinkled with wet " rouge " (a carefully calcined 
sulphate of iron), gives the glass held against it a beautiful 
polish without altering its spherical curvature. The same 
processes must now be gone over with the other surface of 
the lens, after which it is cleaned and cut with a diamond 
to a shape suitable for its future mounting, and its edges 
dressed. 

In grinding a cylindrical lens the surface of the tool is, 
of course, a portion of the, surface of a cylinder; and the 
glass is ground by a to-and-fro motion. It is evident that 
the axis of the cylinder in the future spectacle need not be 
taken into account in grinding, but only in the process of 
cutting to shape for mounting. As a matter of fact, very 
few cylinders are, at present, ground in this country : 
the glass is brought from Europe with a cylinder 
already ground upon one side and glued to its block 



32 SPECTACLES AND EYEGLASSES. 

of iron for the grinding of a spherical or plane surface 
upon the other. 

When the lenses are of high power it is of advantage 
that they be made in the form of a meniscus, giving what 
are known as periscopic glasses. For instance, if a + 4. 
diopter lens is required, the anterior surface is ground to a 
-f 6. D. and the posterior surfaces to a — 2. D. It is just 
as advantageous to a cylindrical or sphero-cylindrical glass 
to be periscopic as it is to a spherical, but, under present 
methods of grinding, it is manifestly impossible to give 
them this form, as the cylinder is ground on one side, and 
the other ground to a plane or sphere as the case may be. 
Glasses which overcome the difficulty have, however, been 
made, and were described by Dr. George C. Harlan at the 
meeting of the American Ophthalmological Society in 1885, 
and again in 1889. From the latter communication I quote 
the following description of the glass : — 

" The lens to which I wish again to call the attention of 
the Society consists of crossed cylinders ground on one sur- 
face of the glass, the other being left for any desired spheri- 
cal curve. In this way a meniscus may be produced. 
Here, for instance, is a combination lens giving the effect 
of + 4. O + 2. Cyl. To produce this effect crossed cylin- 
ders of + 4- an d + 6. are required, supposing the other 
surface of the glass to be left plain. If we wish to give the 
periscopic form to this glass, it can be done by making the 
cylinders 6 and 8, and grinding a — 2. sphere on the other 
side. If a simple cylinder is needed, the spherical curve 
must equal that of the weaker cylinder. 

" I learn from a recent publication by Dr. George J. 
Bull, of Paris, entitled ' Lunettes et Pince-nez,' that glasses 
similar to these have been made with more or less success 
before, but have never come into general use. Dr. Bull 



GENERAL CONSIDERATIONS. 



33 



describes them under the name of ' verves toriques! The 
tore (Latin torus) is the surface engendered by a circle 
which turns about an axis situated on the plane of the 
circle. A familiar example of the torus is the circular con- 
vex moulding at the base of an architectural column. A 
glass ground upon a wheel having this form will present 
two cylindrical curves, at right angles to each other, one 
depending on the radius of the wheel, and the other on the 



Fig. 





radius of the convexity of its rim. It would seem that 
' toric lenses' is the proper designation of these glasses." 
Fig. 4, A, represents a concave toric lens. In the same 
figure, b is a concave cylindrical lens, introduced for the 
sake of comparison. 

Those who have used these glasses consider them much 
more satisfactory than glasses made by the common method, 
and they should be borne in mind when prescribing for 
3 



34 SPECTACLES AND EYEGLASSES. 

high astigmatism in patients who use their eyes a great 
deal for work requiring accuracy. 

Eye Wires, Temples and Bridges. — Eye wires are 
made by wrapping the untempered wire, in the form of a 
spiral, closely about a flattened metal cylinder. Being 
tempered while in this position, the loops of the spiral will 
retain the shape given them. A single cut down the side 
of the cylinder converts each loop into a separate oval ring. 
End pieces and straight temples are stamped from sheets of 
metal, and afterward formed and tempered. Hook temples 
of steel are turned from wire upon a lathe. Bridges are 
usually made of oval or half oval wire, and are simply 
pressed to the desired shape by a forming machine. 

Of the Different Patterns of Spectacles. — In the com- 
mon and strongest form of spectacle, the edge of the glass 
is bevelled so as to enter a groove in the wire which sur- 
rounds it. In a second form, in which the edge of the 
glass is grooved for the reception of a fine, round wire, the 
object sought, of rendering the rim of the spectacles less 
conspicuous, is generally defeated by the fact that the glass 
must be made thicker than it otherwise need be, in order to 
give room for the groove on its edge. In concave glasses 
this is not the case, since the edge of the glass is here the 
thickest part, and such glasses may sometimes be mounted 
in this way with advantage. In a third form, called " frame- 
less " spectacles (Fig. 5), the wire encircling the glass is 
dispensed with altogether, small holes being drilled through 
the glass near its edge for the accommodation of screws 
which fasten the bridge and temples in place. The advan- 
tages of this form are its beauty and inconspicuousness. It 
should never be prescribed for children, as it is quite liable 
to break at the point where the glass has been drilled. The 
edges of these glasses should not be polished, but should 



GENERAL CONSIDERATIONS. 



35 



be given a dull finish, otherwise they reflect the light 
disagreeably. 

Sides, or temples, have been variously constructed. 
Those having sliding and turn-pin joints are examples of 
antiquated forms. Those now used are the " hook," or 
44 riding-bow," and the plain, " straight " temple. The 
former are to be preferred in all cases where the glasses are 



Fig. 5. 




to be worn constantly or nearly so, and the latter for those 
who wear glasses for near work only, and require to remove 
them frequently from the eyes. Hook temples are made 
in three lengths, designated as short, medium, and long. 
These are sufficient for all cases. 

Securing a proper fit in the bridge, upon which so much 
of the comfort and efficiency of spectacles depends, was a 
difficult matter until the ingenuity of Dr. Charles Hermon 



36 



SPECTACLES AND EYEGLASSES. 



Thomas, of this city, suggested what is known as the 
"saddle bridge," which solved the problem. (See Fig. 6.) 
This bridge may be varied to suit every possible case, and 
is always to be preferred. The " K " bridge, formed of 
wires in the shape of the letter K, is allowable in some 
cases. The nearly similar " X " bridge allows the glasses 
to teeter, or see-saw across the nose, with the motions of 
the head. The old-fashioned bridge called the " curl," is 
unobjectionable for cases in which the bridge of the nose 



Fig. 6. 




" X," " K," " Curl," and " Saddle" Bridges. 

is prominent, or for the spectacles of old people, who like 
to slip their glasses down toward the end of the nose. None 
of the forms mentioned, however, have any advantage over 
the saddle bridge for any case. A small piece of cork is 
sometimes attached to the under side of the bridge where 
it comes in contact with the skin. It is unnecessary if the 
frames fit the face of the wearer properly. If it be desir- 
able to remove all pressure from the bridge of the nose and 
to transfer it to the sides, it is best done by soldering a 



GENERAL CONSIDERATIONS. 37 

pair of guards, similar to those used on eyeglasses, to the 
spectacle bridge. 

The earliest spectacles appear to have had round eyes. 
Various other shapes are occasionally seen, as octagon, 
oblong, etc. The oval has about displaced these antiquated 
forms, and is made in sizes known to the trade in America 
as follows : — 



No. oo 
" o, 



TABLE I— SIZES OF EYES. 
ii| by il in. or 41 by 32 mm. large coq. size. 
l|| by ii| in. or 39 by 30 mm coq. size. 
I Te ky 1 J i n - or 37 by 2 8 mm. standard large eye. 
I ii by II in. or 36 by 25 m:n. standard E. G. size. 
1 1 by I ¥ V in. or 35 by 26 mm. standatd interchange. 
il| by f i in. or 34 by 25 mm. standard small eye. 
r i by f| in. or 32 by 23 mm. children's size. 



Where glasses are used for near work only, the eyes are 
sometimes made of semi-oval shape, allowing the line of 
sight to pass over their upper, straight edge when the 
wearer views a distant object. These are known as " half," 
" pulpit," or " clerical " eyes, and are very convenient, 
especially to public speakers, as their name implies. They 
do not seem to me as well known or as generally used 
as they should be. 

When glasses of different focussing power are required 
for distant and near vision, the trouble incident to frequent 
changing is obviated by "bifocal" glasses. That is, the 
lower part of the spectacle eye, which is used for near 
work, is made to differ in focussing power from the upper 
part, which is used for distant vision. Such bifocal glasses 
are also called Franklin glasses, from the philosopher who, 
as we have seen, invented them. 

The object sought may be attained in various ways. In 
the early Franklin glasses each eye contained two half oval 



38 



SPECTACLES AND EYEGLASSES. 

Fig. 7. 









Ovals Showing the Actual Sizes of Eyes According to Table I. 



GENERAL CONSIDERATIONS. 



39 



pieces, with their straight edges in apposition (a, Fig. 8). 
This has been improved upon by making^the line of junc- 
tion a curved one, giving somewhat greater latitude of 
distant vision and rendering the glass more secure in its 
frame. A form of bifocal glasses which w T ere never used to 
any great extent are called " ground " bifocals. They are 
very handsome, containing only one piece of glass in each 
eye, the upper and lower parts of which are ground of dif- 
ferent strengths (c, Fig. 8). The mechanical impossibility 



Fig. 





c^> 



o 



of centering both spherical surfaces upon the same piece of 
glass, however, introduces a prismatic effect which destroys 
their usefulness. The latest and best variety of these glasses 
are called "cemented bifocals" (d, Fig. 8). They have 
been in occasional use in France for over twenty years, 
though their general manufacture by our opticians is due 
to the efforts of Dr. Geo. M. Gould. To the back of the 
distance glass is cemented, by means of Canada balsam, 
a small lens whose strength added to that of the distance 



4-0 SPECTACLES AND EYEGLASSES. 

glass equals the strengh required for near work. The 
upper edge of the supplemental lens should be ground as 
thin as possible, in order to render it inconspicuous. This 
nearly does away with the objectionable line of junction, the 
spectacles are strong, light and handsome, and may even 
be made " frameless," like those represented in Fig. 5, if the 
patient so desire. For cylindrical lenses this form is also 
cheaper, since only the distance glass need have the cylin- 
der ground upon it, the supplemental segment being a 
simple sphere. 

All bifocals have the inconvenience that in walking, the 
floor just in front of the patient's feet is not seen clearly 
because viewed through the near glass. Spectacles which 
revolve on the long axis of the " eye/' bringing the distance 
glass to the lower portion of the frame, have been contrived 
to overcome this difficulty, but they are cumbersome and, 
moreover, it requires more effort to effect the revolution 
of the glass than it does to bend the neck sufficiently to 
bring the upper segment into the line of vision when the 
ordinary bifocals are worn. Some persons declare that 
they cannot become accustomed to bifocals however well 
adjusted. Parallel, horizontal lines, as those of a staircase, 
are particularly confusing, it being possible to see each line 
doubled if the junction of the two segments of the glass 
is placed just opposite the pupil. Such persons may prefer 
having an " extra front " (Fig. 9) : that is, a second pair of 
spectacles whose temples are replaced by short hooks, by 
means of which they are hung in front of the frame already 
upon the face. This is a rather clumsy device ; less so, 
however, when the eyes of the extra front are made half 
oval instead of oval. 

Eyeglasses. — Most that has been said of the varieties 
of spectacle frames applies as well to eyeglass frames. As 



GENERAL CONSIDERATIONS. 
Fig. 9. 



41 




Fig. 10. 




f^mmmmmm^ 




Forms of Rigid Frame or " Bar Spring" Eyeglasses. 
4 



4^ SPECTACLES AND EYEGLASSES. 

was mentioned, the chief objection to the latter is that they 
allow a displacement of the axis of a cylindrical, or base 
of a prismatic lens. This is a necessary concomitant of 
their being joined by a spring instead of a rigid bridge. 
More or less ingenious frames have been made in which 
the glasses are rigidly joined, and the spring placed in some 
other position (Fig. 10); their weight and cumbersome 
appearance have, however, so far prevented their becoming 
popular. Another difficulty arises from the fact that it is 
impossible to always place the glass at the proper distance 

Fig. ii. 



from the eye, since the frame must be placed at that point 
where it obtains the best grip upon the sides of the nose. 
This has been in great measure overcome by what is called 
the " offset guard," in which the nose-pieces are placed 
back of the plane of the glasses, instead of in the same 
plane, as formerly. When the glasses contain no prism or 
cylinder, or only weak cylinders, a well adjusted eyeglass 
with " offset guards " is fairly satisfactory. When made 
frameless, as in Fig. 1 1, it is the most modern, and certainly 
the most handsome mounting we have to offer our 
patients. 



GENERAL CONSIDERATIONS. 43 

Spectacles for Cosmetic Effect. — Something may 
legitimately be done, at times, in the way of improving the 
appearance of a patient by the application of glasses. The 
blind whose eyes are not only sightless, but unsightly, 
very commonly hide them behind colored glasses. Neatly 
fitting spectacles with large eyes of ground glass render 
the appearance of such persons less lugubrious. When 
one eye is useless for vision, and at the same time small, 
and the orbit undeveloped, a gratifying improvement in 
the appearance of the patient may be attained by placing 
before the shrunken eye a convex glass of sufficient strength 
to magnify it to the size of its fellow. The condition 
known as epicanthus can generally be removed by wearing 
eyeglasses whose nose pieces draw just enough on the inner 
canthi to smooth out the offending fold of skin. As the 
subjects of epicanthus are generally flat-nosed, it may be 
necessary to furnish the eyeglasses with a pair of hook 
temples to keep them in place. Since operations for this 
disfigurement are so unsatisfactory, such an appliance is 
probably the best treatment we can advise in case the 
trouble is not outgrown. 



II. THE PRINCIPLES OF SPECTACLE FITTING. 

We have now to consider the essential principles of plac- 
ing glasses before the eyes. The usefulness of spectacles 
depends almost as much upon the fidelity with which these 
principles are carried out as it does upon a careful correc- 
tion of the errors of refraction. 

Centering and Decentering. — By the visual axis, or, in 
English, the line of sight, is meant a line from the yellow 
spot of the retina through the nodal point of the eye to the 
object sighted. 

By the principal axis of a lens we mean a line passing 
through the optical center of the lens (the thickest part, if 
the lens is convex ; the thinnest if concave) at right angles 
to its surfaces. 

The geometrical center of a spectacle glass may be 
shortly said to be that point on its surface which is equally 
distant from the extremities of the figure to which it is cut. 
The principal axis of the lens mayor may not pass through 
this latter center. 

We habitually regard as the normal position for glasses 
one in which, when the eyes are looking at a distant ob- 
ject, the visual axes correspond exactly in position with 
the principal axes of the lenses, and together they pass 
through the geometrical centers of the spectacles. In 
other words, the geometrical center of the spectacle eye 
and the optical center of the spectacle lens coincide, and 
the center of the pupil for each eye lies directly behind 
them. Regarding decentering, some confusion is apt to 

44 



THE PRINCIPLES OF SPECTACLE FITTING. 45 

arise because the word is used in two different connections. 
If the visual axis pass to the temporal side of the optical 
center of a glass held before an eye, then, with respect to 
that eye, the glass is said to be " decentered in." If the 
visual axis pass to the nasal side of the optical center of 
the glass, the latter is " decentered out." Similarly a glass 
may be decentered in any other direction. When speak- 
ing of spectacles, however, without reference to the eyes 
of the wearer, they are said to be " decentered in," when 
their optical centers lie to the inner side of their geomet- 
rical centers ; " decentered out " when the optical centers 

Fig. 12. 




Spectacles with Lenses Decentered in. 

G G show the position of the geometrical centers; O O that of the optical 
centers. 



are to the external side of the geometrical centers, etc. 
A glance at Fig. 12, which represents a pair of spectacles 
decentered in, will make clear what is meant. 

From the above it will readily be seen that when it is 
desired that a patient wear decentered lenses, the effect 
may be obtained in either of the two ways : first, by 
decentering the lenses in their frame ; second, by dis- 
placing them, together with their frames, from what I have 
described as the normal position. The first method has 
the disadvantage of increasing the weight of the glass, 
while the second limits the field of binocular vision. In 



46 SPECTACLES AND EYEGLASSES. 

practice, the second method should be employed to the 
greatest extent possible without unduly interfering with 
binocular vision for the distance at which the spectacles 
will be used, and, should still farther decentering be 
required, the method first mentioned should be brought 
into service. For instance, suppose we wish to order 
glasses with each lens decentered in 8 mm. This would 
mean that the optical centers are to be 16 mm. nearer 
together than the patient's pupils. Let us suppose that by 
a careful consideration of the distance for which the glasses 
are prescribed, of the distance at which they must be 
placed in front of the eyes, and of the size of the spectacle 
eye used, we find that the frame can only be made 10 mm. 
narrower than normal without the outer rims of the " eyes" 
becoming annoying. This leaves 6 mm. to be obtained 
by decentering the glasses in their eye-wires. If the dis- 
tance between the patient's pupils were 60 mm., we would 
order the distance between the geometrical centers of the 
spectacle eyes to be 50 mm., and each eye to be decentered 
in 3 mm. 

Prismatic Effect of Decentering. — It is to obtain a 
prismatic effect from spherical lenses that decentering is 
generally ordered, since a decentered lens is identical with 
a lens of the same strength combined with a prism. This 
is graphically shown by Figs. 13 and 14, the latter of 
which represents a section of a decentered lens, which will 
readily be seen to be precisely the same as the result would 
be if the normally centered lens shown in Fig. 13 were 
split into halves and the prism b a c introduced between 
them. 

The size of the glass disks from which spectacle lenses 
are ground will not allow of more than about 2 mm. of 
lateral decentering for a No. 1 "eye;" 3 mm. for Nos. 2 



THE PRINCIPLES OF SPECTACLE FITTING. 



47 



and 3 ; and 4 mm. for No. 4. Vertically, they may be 
decentered much more. When ordered to decenter later- 
ally more than this, or to furnish a prismatic effect greater 
than can be obtained by this much decentering, the optician 
first manufactures a prism of the requisite strength, and 
then grinds spherical surfaces upon its two faces. It is, 
therefore, of not much importance whether, in ordering a 
sphero-prismatic combination, we express the prismatic 
element in degrees of the refracting angle, or in millimeters 
of decentration of the lens : the optician produces the glass 
by whichever method is most convenient. 



Fig. 



Fig. 14. 





Showing the Prismatic Effect of Decentering. 

The optical center, O, in Fig. 13, coincides with the geometrical center, G, 
in Fig. 14, which represents a decentered lens of the same spherical 
curvature ; O has been removed towards the base of the virtual prism bac. 
{After Maddox.) 



The stronger the lens, the less decentering it requires to 
produce a given prismatic effect, and where the combina- 
nation desired is that of a strong lens with a weak prism, 
the more accurate practice probably is to order the lens 
decentered the requisite number of millimeters. For this 
purpose a table of equivalents, such as is given below, is 
necessary. To use it, we find in the first column the 
strength of the lens used, and on a level with this, in the 
column at whose head stands the strength of the prism re- 
quired, is given in millimeters the amount of decentration 
necessary. 



48 SPECTACLES AND EYEGLASSES. 

TABLE II*— DECENTERING EQUIVALENT TO A GIVEN RE- 
FRACTING ANGLE (TNDEX OF REFRACTION, 1.54.) 



Lens 


i° 


2° 


3° 


4° 


5° 


6° 


8° 


IO° 


1 D, 


94 


18.8 


28.3 


37-7 


47.2 


56 5 


75.8 


95 2 


2 


4-7 


9-4 


14 1 


18.8 


23.6 


282 


37-9 


47.6 


3 


3-i 


6-3 


9-4 


12.6 


i57 


18.8 


25-3 


3*-7 


4 


2-3 


4-7 


7-1 


94 


11.8 


1 4.1 


18.9 


23.8 


5 


1.9 


3-8 


5-7 


7-5 


9-4 


"•3 


15.2 


19. 


6 


1.6 


3-i 


4-7 


6.3 


7.9 


9-4 


12.6 


15.9 


7 


i-3 


2.7 


4- 


5-4 


6.7 


8.1 


10.8 


13-5 


8 


1.2 


2-3 


3-5 


4-7 


5-9 


7-i 


9-5 


11.9 


9 


1. 


2.1 


3.1 


4.2 


5.2 


6.3 


8.4 


10.5 


10 


•9 


1.9 


2.8 


3-8 


4-7 


5.6 


7.6 


9-5 


11 


•9 


i-7 


2.6 


35 


4-3 


5 1 


6.9 


8-7 


12 


.8 


1.6 


24 


3-i 


3-9 


47 


6.3 


7-9 


13 


•7 


i-4 


2.2 


2.9 


3-6 


4-3 


5.8 


7-3 


H 


•7 


1-3 


2. 


2-7 


3-4 


4. 


5-4 


6.8 


15 


.6 


1.3 


1 9 


25 


3-1 


3-8 


5-i 


6-3 


16 


.6 


1 2 


1 8 


2.4 


3- 


3-5 


4-7 


6. 


17 


.6 


1.1 


1 7 


2.2 


2.8 


3-4 


4-5 


5-6 


18 


•5 


1. 


1.6 


2.1 


2.6 


3-1 


4.2 


5.3 


19 


•5 


1. 


i-5 


2. 


2-5 


3- 


4- 


5- 


20 


•5 


•9 


1-4 


i-9 


2.4 


2.8 


3* 


4.8 



A cylindrical lens, or the cylindrical element of a sphero- 
cylindrical lens, when decentered in a direction vertical to 
its axis, acts as a spherical lens of the same strength. 
Thus, a -\-2. Sph. o +1. Cyl. axis vertical, decentered 
horizontally, would have the same prismatic effect as a +3. 
Sph. treated in the same way. As the axis is inclined 
toward the direction of decentration, the prismatic effect of 
the cylinder diminishes, and disappears when they coin- 
cide. Thus, a +2. Sph. CD +1. Cyl. axis horizontal, de- 
centered horizontally, would have merely the prismatic 
effect of a +2. Sph. so treated. 

* Jackson: "Transactions of the American Ophthalmological jSociety," 
1889. 



THE PRINCIPLES OF SPECTACLE FITTING. 49 

Normal Lateral Centering. — In proportion as the 
prismatic effect of decentered lenses is a valuable property 
where this effect is desired, it has to be guarded against in 
those cases which do not require it, to which number 
belong, of course, the great majority of the cases we are 
called upon to treat. If the objects looked at through 
spectacles were always situated in the same direction and 
at the same distance, fixing the position proper for the 
centers would be a simple matter ; but, in the movements 
of the eyes, each pupil roves over a territory some 18 mm. 
(^ in.) long by 15 mm. broad. When the eyes are directed 
toward a distant object the centers of the pupils are about 
60 mm. apart, and on convergence only 56 mm., so that 
the proper adjustment of spectacles is a series of comprom- 
ises between that proper for the position of the eyes in 
which the glasses will be most used and other positions in 
which they will be less used. Of course, the position in 
which they will be most used must receive the greatest 
consideration. 

The proper position for the centers of " distance " glasses 
has already been stated. When glasses are to be used for 
near work only, they should be decentered " in " two or three 
millimeters on each side from this " normal " position, as 
such glasses being never used in that position, but only 
when the visual axes are converged, would otherwise never 
be rightly centered. What amounts to the same thing, and 
is more often done, is to make the front of the near specta- 
cles four or six millimeters narrower than if they were 
intended for distant vision : four millimeters narrower for a 
working point of 15 inches; six millimeters narrower for 
one of 10 inches. Concerning the centering of glasses 
which are worn constantly, no rule for all cases can be laid 
'down, since accurately centering for any one distance is 



5<3 SPECTACLES AND EYEGLASSES. 

decentering for every other. Fortunately, as a glance at 
Table II will show, it is only with lenses of high power 
that a considerable amount of prismatic effect is developed 
by slight decentering. Where such glasses must be worn 
constantly by a person who spends several hours daily at 
near work, they should certainly be slightly decentered 
inward. 

The distance between the geometrical centers is regulated 
by the size of the spectacle eyes and the width of the space 
between them occupied by the bridge. Where the inter- 
pupillary distance is short, as in children, opticians are apt 
to make the eyes of the spectacles so small as to interfere 
seriously with the field of vision through them. With the 
saddle bridge there is no difficulty in diminishing the space 
between the spectacle eyes without interfering with the form 
of that part of the bridge which is applied to the nose, and 
the required adjustment should be made in this way ; leav- 
ing the spectacle eyes of good size. 

Normal Vertical Centering. — The glasses require, fur- 
ther, to be so placed that the points where the wearer's 
visual axes penetrate them shall neither be above nor below 
the centers. This adjustment is readily seen to depend 
upon the relative height of the bridge of the spectacles and 
the bridge of the nose at the point where the spectacles 
rest. The higher the spectacle bridge, the lower will the 
glasses stand upon the patient's face, and vice versa. 

On the bridge of nearly every nose there may be felt a 
point at which the narrow, upper portion of the nasal bones 
gives place rather suddenly to the broader lower portion. 
Just here, in what has been called the " natural " position 
(a, Fig. 15), the bridge of the spectacles tends to rest, and 
the attempt to make it remain at any other point will not 
be very successful. In distance spectacles, then, the bridge 



THE PRINCIPLES OF SPECTACLE FITTING. 5 I 

should be made of such height that when resting at this 
natural position the centers of the spectacle eyes are at the 
same height as the centers of the pupils when the patient 
looks straight forward. When the glasses are to be used 
for near work only, their bridge should be made about 
2 mm., or y& inch higher than otherwise, allowing the 
centers to drop that much lower, as the wearer's eyes 
will nearly always be directed to objects below their 
own level. 

Fig. 15. 



Distance of the Glasses from the Eyes. — As a rule, 
the glasses should be placed just far enough from the eyes 
to escape the lashes in the act of winking. If the lashes 
touch the glass the latter quickly becomes soiled, and to the 
spectacles is, moreover, attributed any falling out of the lashes 
which may occur. Some persons, however, with myopia 
of high degree, prefer the glasses to be placed as close to 
the eyes as possible, regardless of the lashes, because of 
the larger clear images which they thus obtain. This 
adjustment of the glasses depends upon the relation of the 
top of the spectacle bridge to the plane of the glasses. 



52 



SPECTACLES AND EYEGLASSES. 



Where the eyes are deep set, or the nose of the aquiline 
type, the top of the spectacle bridge must be in front of the 
plane of the glasses, or, as it is shortly called, "out" 
(Fig. 16). When the bridge of the nose is low and the 
eyes relatively prominent, as in the negro, Chinese and 
children, the top of the bridge must be back of the plane 
of the glasses, or " in," as represented in Fig. 17. 

Perpendicularity of the Plane of the Lenses to the 
Visual Axis. — A very important requirement, and one 
not sufficiently regarded in the fitting of frames, is that the 
plane of the correcting lens when in use shall be as nearly 



Fig. 16. 



Fig. 17. 




1 (X 




as possible perpendicular to the visual axis. The stronger 
the lens the more important is this detail, whose warrant 
lies in the fact that the refractive value of a given lens 
placed obliquely to the visual axis is no longer that indi- 
cated by its number, but is that of some other, stronger 
lens. A cylindrical lens so placed acts simply as a 
stronger cylindrical lens ; a spherical lens, however, as 
a stronger spherical lens combined with a cylindrical 
lens with its axis at right angles to that about which 
the lens is rotated. 

The results of the investigations of himself and others, of 
the effect of the obliquity of a lens to an incident pencil of 



THE PRINCIPLES OF SPECTACLE FITTING. 



S3 



rays, was summarized by Dr. Edward Jackson, in a paper 
read before the American Medical Association in 1877, and 
their practical application to this part of our subject pointed 
out. From that communication the following table is 
extracted. It gives in the first column the degrees of 
obliquity at intervals of 5 up to 45 °. In the second 
column is shown the refractive value of a 1. D. cylindrical, 
in the third that of a 1. D. spherical lens so inclined. 



TABLE III. 



Obliquity 


Refractive power of a 


Sphero-Cylindrical Equivalent 


of 


1 D. Cylindrical 


of a 1 D. Spherical Lens 


the Lens. 


Lens so Placed. 


so placed. 


o° 


I. D. cyl. 


I. D. spherical. 


5° 


1. 01 " 


1. 00 sph. 3 °- 01 c yi- 


IO° 


1.04 " 


1. 01 sph. 3 ° °3 c yi- 


i5° 


1. 10 " 


1.02 sph. 3 °-°8 cyl. 


20° 


1. 17 


1.04 sph 3 °- I 3 c yi- 


25° 


1.30 


1.06 sph. 3 0.24 c\l. 


30° 


1.44 


1.09 sph. 3 0.36 cyl. 


35° 


1.69 " 


1. 12 sph. 3 0.56 cyl. 


40° 


2.01 " 


1. 16 sph. 30.83 cyl. 


45° 


2.46 " 


1.22 sph. 3 : - 2 4 c yi- 



To. fulfil this requirement of perpendicularity to the visual 
axis, the lenses of spectacles used only for distance should 
lie in a vertical plane ; that is, they should face directly 
forward, as shown in Fig. 18. Since the visual axes are 
directed downward and forward when near work is done 
below the level of the eyes, glasses for near must face down- 
ward and forward, as in Fig. 19, in order that the plane 
in which they lie shall be perpendicular to those axes. 
Furthermore, in viewing near objects the visual axes are 
directed inward and toward each other. This will require 
the glasses to face inward also, as represented in Fig. 20, 



54 



SPECTACLES AND EYEGLASSES. 
Fig. i 8. 




Fig. 19. 




THE PRINCIPLES OF SPECTACLE FITTING. 55 

so that they come to lie in different planes, instead of in the 
same plane as formerly. 

When " constant " glasses are prescribed, the lenses 
should be placed midway between the proper facing for 
near and that for distance glasses. Then, though the lens 
is not exactly properly inclined either for distant vision or 
near work, the result of such slight obliquity to the 
visual axis is unimportant, since, as a reference to Table 
III will show, it is only in the higher degrees of ob- 
liquity that the increase in power, and especially the 
development of cylindrical effect from spherical lenses is 
rapid. Moreover, by slightly bending the neck a moderate 

Fig. 20. 




degree of obliquity of the glasses to the visual axes may be 
removed without discomfort to the wearer. 

The position of bifocal glasses should also be between 
that proper for near and for distance glasses, but nearer that 
of the stronger glass. This will generally be the near glass, 
as convex bifocals are much more frequently prescribed 
than concaves, and such glasses should face only a little 
less downward than glasses intended entirely for near 
work. When concave bifocals are worn, however, they 
should face more forward and much less downward. 

The angle which the plane of the glasses makes with the 
plane of the wearer's face depends entirely upon the angle 
formed by the plane of the glasses and the temples of their 



$6 SPECTACLES AND EYEGLASSES. 

containing frames. Thus, when the temples are perpen- 
dicular to the plane of the glasses, as in Fig. 18, the latter 
will face forward and not at all downward. They may be 
made to face downward to any required degree by simply 
turning down the temples at the points where they are 
hinged to the end pieces. These must be equally turned 
down, however, as where only one is turned down, or one 
more so than its fellow, the result is not to make the glasses 
face downward, but to make the glass on the side of the 
lower temple ride higher on the face than its fellow. 

Periscopic Glasses. — In the effort to further apply the 
law requiring that the plane of the lenses shall be perpen- 
dicular to the visual axes, we are met with the fact that with 
biconvex and biconcave lenses this relation is only strictly 
possible within a comparatively limited area surrounding 
the optical center of the lens. When the wearer looks 
through the periphery of his glasses the visual axes will 
pierce the lenses obliquely, and the refractive value of the 
latter will, of course, be governed by all the laws of tilted 
lenses. For instance, when the wearer of an ordinary 
convex lens looks through it near the edge, the optical 
effect of the glass before his eye is that of a stronger convex 
lens combined with a cylindrical lens ; the axis of the 
latter depending on the part of the periphery pierced by 
the line of sight. In weak lenses, the slight inaccuracy 
of vision produced in this way is of small moment, but 
where the strength of the lens used is greater than about 
2. D. the patient's field of accurate vision is greatly 
reduced in size, and in viewing objects not directly in 
front of him, he is obliged to perform wide motions of the 
head in order to be able to see them through the central 
portion of his glasses. This is especially true of cases 
of aphakia, where, of course, very strong lenses are 



THE PRINCIPLES OF SPECTACLE FITTING. 57 

generally necessary. To escape or lessen these disad- 
vantages, strong spherical lenses should be, and generally 
are, made in the form of a meniscus, which when placed 
with its convex surface from the eye constitutes a peri- 
scopic glass. The ideal of this form of lens may be defined 
as a glass in which the center of curvature of one surface 
coincides with the center of rotation of the eye, and that 
of the other surface approaches it as closely as the required 
strength of the glass will permit. In such a glass the visual 
axis will always be perpendicular to the first surface, and 
nearly so to the second, at whatever point it pierces the 
glass, and in whatever direction the eye may be turned. 

When a cylindrical or sphero-cylindrical lens is required, 
the best form of glass is the toric lens described on page 
33. These lenses have, however, never been manufactured 
extensively, and the process of their manufacture, as well 
as the lens itself, being patented in this country, their cost 
is considerable. By transposing the usual formula, however, 
there may be obtained from any optician a sphero-cylin- 
drical lens which approaches the periscopic form, and is 
certainly superior to one ground after the usual method. 
For illustration, if one desires to order -f 2. D. Sph. O + 
.75 D. Cyl. Ax. 90 , the formula may be transposed and 
the order written for + 2.75 D. Sph. O — .75 D. Cyl. Ax. 
180 . This glass, though optically of the same strength as 
the first, would have an approach to the periscopic form 
if placed with the cylindrical surface next the eye. The 
field of accurate vision would gain in all directions, 
especially in the vertical one, in which diameter, however, 
its enlargement is not of so much consequence as it is 
laterally. Aphakic eyes offer the best field of usefulness 
for this practice, as in them we have generally to deal with 
a high hyperopia, and often with hyperopic astigmatism 
5 



58 SPECTACLES AND EYEGLASSES. 

requiring for its correction a convex cylinder with its axis 
horizontal. Let us suppose that after a cataract extraction 
we wished to order + 10. D. Sph. o + 6. D. Cyl. Ax. 180 . 
With this lens, accurate vision would be limited to a 
vertical oval field situated directly in front of the patient, 
beyond the confines of which all objects would appear 
distorted by various cylindrical effects. We would, 
therefore, transpose the formula into -f 16. D. Sph. O 
— 6. D. Cyl. Ax. 90 , and this glass will be likely to give 
the patient much more satisfaction than the other would 
have done, as with it he obtains a very good lateral field. 



III. PRESCRIPTION OF FRAMES. 

In order to prescribe the frames for a pair of spectacles, 
we must, after measuring the face or a frame which fits, 
record the dimensions of the frame we desire to order. 
The essential measurements are the intercentral distance, 
or width of front, and the three dimensions of the bridge. 
This list may be extended to include the measurement of 
the angle formed by the bridge and the plane of the lenses, 
that formed by the temples and the plane of the lenses, 
the distance between the temples an inch back of the 
glasses, and the distance from the hinge of the temples to the 
top of the wearer's ear. All these details are, however, so 
ready of adjustment, and the trouble and uncertainty of 
their prescription are so great, that in my judgment they 
are better left until the frame is received from the maker 
and we are ready to adapt it to the patient's face. The 
distance between the centers of the spectacle eyes is best 
obtained by measuring upon the face the distance between 
the centers of the pupils ; the other dimensions of the frame, 
however, are more easily obtained by trying on a sample 
frame and taking the measurements from this, estimating 
any change which may be necessary. To do this requires 
about a half-dozen sample frames whose bridges are of 
different dimensions ; also a rule graduated in millimeters, 
or sixteenths of an inch. I have had made for this pur- 
pose a rule which I think facilitates the work. As repre- 
sented in Fig. 21, it has upon one side three scales gradu- 
ated in millimeters and conveniently placed for taking the 

59 



6o 



SPECTACLES AND EYEGLASSES. 







< 
ft, 

w 
u 

H 



cC 







u 


h 








h-1 


1- 


H 


< 


0_ 


J 


p 


o 


ta 






C4 



< 




r- 




< 


2 


fe 
j 


J 




< 


r 


&3 


i 


CL 


> 


w 




2 


z 










u 


u 




X 






1- 


<* 




>• 


fa 
o 




03 






kJ 


^ 




Q 


> 




£ 


c 
2 





PRESCRIPTION OF FRAMES. 6 1 

different dimensions of the frame, while on the reverse 
side are several ovals showing the principal sizes of spectacle 
eyes. Some of the uses of these scales are shown in Figs. 
22, 23, 28, and 29; to avoid confusion, one scale only is 
drawn in each diagram. 



Philadelphia, 189 

Name of Patient ', 

R. 

O. D 

O. S. 

Unless otherwise specified, furnish the following: Medium length temples; 
saddle bridge ; No. 2 eyes. Dimensions are given to middle of wires. Dimen- 
sions given are in millimeters. 

Frames of & j Catalogue No 

Interpupillary Distance 

(■«** Top ™ 

Bridge X 

I Width of Base 



M. D. 



A prescription blank such as that here given indicates 
what measurements are required, and will be found useful 
in practice. The upper part is for the lenses, the lower 
part for the frames. 

To Obtain the Interpupillary Distance, with which 
the first dimension of the frame, the distance between the 



62 



SPECTACLES AND EYEGLASSES. 



geometrical centers (a to b, Fig. 22), is generally identical, 
the physician seats himself facing the patient in a good 
light, the latter being directed to look straight before him 



Fig. 




at some distant object. The measuring rule is placed be- 
fore the patient's eyes, as close to them and as far from the 
physician's eyes as possible. The zero of the scale being 
placed opposite the center of one pupil, the center of the 



Fig 23. 




other may be marked by the physician's thumb nail, as 
represented in Fig. 23, and the distance between them read 
off the scale. This distance seldom varies more than 5 mm. 



PRESCRIPTION OF FRAMES. 63 

from 60 mm., or 2}i in. It will be observed that as the 
physician's eyes are less than the length of his arm away 
from the patient's face when this measurement is taken, 
in fact about two feet away, the marks upon the rule, though 
apparently opposite the pupils, will in reality be a little 
within the centers ; so that the distance obtained will be 
a little less than it should be. When the physician's eyes 
are two feet away from those of the patient, and the rule 
is one inch away from them, the error in measuring an 
interpupillary distance of 60 mm. by this method is almost 



Fig. 



Fig. 24. 





Dr. Maddox' Pupil 
Localizer. 



The Pupil Localizer in Use. 

exactly 2 mm. This amount should, therefore, be added 
to the apparent interpupillary distance to obtain the true 
one. 

The measurement obtained in this way is sufficiently ac- 
curate for most purposes, but if a greater degree of accuracy 
be desired in any case it may be attained by means of the 
little device suggested by Dr. Maddox, which is represented 
in Fig. 24. This is to be placed before one of the patient's 
eyes in an ordinary trial frame having a graduated bar for 
showing the distance of each geometrical center from the 
middle of the bridge. The gaze of the observed and that 



6 4 



SPECTACLES AND EYEGLASSES. 



of the observing eye being directed to each other's pupils 
the two s.ghts of the implement are brought into line be- 
tween them, as shown in Fig. 25. The same procedure 
is then gone through with for the other eye, and the distance 
of the second pupil from the median line of the face, as regis- 



Fig. 26. 




tered by the trial frame, is added to that of the first, to obtain 
the mterpupillary distance. This procedure is also of advan- 
tage in revealing and measuring any difference in the dis- 
tance of the pupils from the median line, due to asymmetry 
of the face. The use of a trial frame for making accurate 



PRESCRIPTION OF FRAMES. 



65 



measurements requires the bestowal of considerable atten- 
tion to see that the support of the nose piece is vertical, 
the joints close and tight, and the markings correct; other- 
wise it may readily introduce the errors its use is intended 
to obviate. There are, in the shops, many special forms 
of the " pupilometer" constructed on the principle of a rule 
held before the eyes and a single sight for each pupil. 
Two of these are shown in Figs. 26 and 27. The interpu- 
pillary distance as registered by them requires, of course, 
the same correction as does that obtained by the simple 
graduated rule. 

Height of the Bridge. — This is the distance of the top 
of the bridge above a line joining the centers of the 

Fig. 27. 




lenses. In Fig. 22, it is the distance from e to f, which is 
the height of e above a line joining A and b; not the 
height of e above a line joining c and d, which is some- 
times erroneously supposed to represent the height of the 
bridge. 

If a rule be held horizontally before the patient's eyes, 
with the lower edge touching the nose at the natural 
position for the spectacle bridge, the height of this edge of 
the rule above the pupil on either side will show at a 
glance about how high the top of the future bridge must 
be. We may then select from our sample frames that one 
whose bridge corresponds most nearly with this supposed 
height, and being sure to place it in the natural position, 
we carefully note w T hether the pupils are above or below 



66 SPECTACLES AND EYEGLASSES. 

the centers of the eyes of the frame. If they are below these 
centers, sufficient must be added to the height of the bridge 
now upon the face to allow them to coincide ; if the 
pupils are above the centers, a corresponding subtrac- 
tion from the height of the trial bridge must be made. 
Each sample frame may have its dimensions attached 
to it, or any frame may be used as a fitting frame 
and afterward measured. To measure the height of a 
bridge the glasses are laid upon a sheet of ruled paper, or 
other object offering a convenient straight line, in such a 



Fig. 




way that the line passes through the geometrical centers ot 
the eyes, or, what is the same thing, through the joints of 
the end pieces on each side (Fig. 22). The height to 
which the bridge projects above this line is then readily 
measured. It is seldom greater than 10 mm., and in rare 
cases may be a minus quantity, the top of the bridge being 
below the level of the centers of the lenses. 

Relation of the Top of the Bridge to the Plane of 
the Lenses. — The measurement required to express this 
relation is that from j to k in Figs 28 and 29 ; not the 
distance of j in front of a line joining c and d, as might 



PRESCRIPTION OF FRAMES. 67 

be supposed. This measurement is also shown at h I, 
Figs. 16 and 17; it is obtained by a procedure similar to 
that just described for obtaining the height of the bridge. 
The rule being placed across the nose at the natural point, 
and the patient requested to wink, it may readily be seen 
whether the lashes touch the edge of the rule. If they do, 
the top of the bridge of the future spectacles must be 
back of the plane of the glasses, or " in." If they do not, 
we note how much nearer, if any, the edge of the rule 
might be brought without their touching, and so obtain 
a guide to the distance the top of the bridge should be in 

Fig. 29. 




front of the plane of the lenses, or " out." The fitting 
frame which comes nearest to the requirements of the 
case in this particular is then placed upon the face, when 
by viewing it from above or from the side it can quickly 
be seen just how much change, if any, is needed to place 
the glasses a little beyond the reach of the lashes. The 
method of measuring the distance of a bridge in or out is 
so plainly shown in Figs. 28 and 29 that special explana- 
tion is unnecessary. They seldom measure more than 
4 mm. out or 3 mm. in. 

Width of Base. — The measurement from c to d, Fig. 
28, is obtained, like the others, by measuring a bridge 



68 SPECTACLES AND EYEGLASSES. 

which fits or estimating the change necessary in one 
which does not. This dimension is usually from 16 mm. 
to 20 mm. 

This method of obtaining the dimensions of the bridge 
required may seem tedious and uncertain in the description ; 
in use it is not so, and after trial I think will be found 
preferable to any special device so far invented for record- 
ing the measurements. These, after shifting of screws and 
bending of wires, leave one to estimate what changes are 
required just as might have been done without their aid. 
Moreover, the heavy parts and lost space in joints of trial 
frames may readily conceal an error of 2 mm., or even 3 
mm. in some measurements ; the large, round eyes with 
heavy rims will not go under the brows, so that the in-out 
measurement of the bridge must frequently be guessed at ; 
and the relation of the upper part of the eye wires to the 
brows is not shown. In fact, they introduce, in my estima- 
tion, quite as many sources of error as they eliminate. 

Where the face is unsymmetrical no exact rules of pro- 
cedure can be given, and considerable ingenuity may be 
required to fit a frame to such a face. If the nose is very 
peculiar, or one side of its bridge markedly steeper than the 
other, it may be of advantage to take an outline of the 
bridge at the natural position by bending a piece of lead 
wire to fit accurately and marking the outline of this upon 
the prescription blank, or sending the wire itself to the 
spectacle maker. Sometimes the brows are overhanging 
and the eyes deep set ; so that the glasses cannot be prop- 
erly centered before the eyes and placed close to them 
without the upper part of the rims burying themselves in 
the brows. In such cases the glasses should be decentered 
upward in their frames and the bridge made sufficiently 
high to bring the optical centers opposite the pupils. Though 



PRESCRIPTION OF FRAMES. 69 

the patient will then look through the upper part of his 
glasses, his field of vision will not be any more limited than 
is already the case because of the overhanging brows. 

Prescription of Eyeglasses. — The dimensions which it 
is usual to furnish in prescribing eyeglass frames are the 
interpupillary distance, of course, with the distance between 
the two upper and the two lower ends of the nose pieces 
when they are in place on the face, (a to b, and c to d, 
Fig. 1 1.) These measurements alone will not insure a good 
fit in the frames, since neither the contour of the sides of 
the nose to which the guards are applied, the vertical cen- 
tering of the lenses, nor the distance of the latter from the 
eyes are taken into account ; but the same remark applies 
here as to the minor dimensions of spectacle frames, 
namely : that it is more simple, certain, and expeditious for 
the surgeon to make these adjustments in the frames them- 
selves than to prescribe what the manufacturer shall do for 
him. Fortunately, eyeglass frames admit of great variation 
by bending their different parts, and being put together 
with screws, these parts are quickly interchangeable. 
Almost the only thing about them which admits of no 
adjustment is the length of the spring, and, it is well for one 
who prescribes many eyeglass frames to have a series of 
such springs at hand from which to replace one which may 
be found too long or too short. 



IV. INSPECTION AND ADJUSTMENT OF SPEC- 
TACLES AND EYEGLASSES. 

Ordinary prudence demands that the prescriber of glasses 
make a careful examination of the manner in which his 
directions have been carried out, since neglect of this pre- 
caution may nullify the results of the most painstaking 
correction of the refraction. If the surgeon himself furnish 
the spectacles, it is doubly incumbent on him to make a 
thorough inspection of glass and frame, and to carefully 
adjust the latter so as to be entirely comfortable to the 
wearer. Then, too, it is not enough that the frames 
correctly perform their function at first ; they must continue 
to do so. Should there be no optician in his neighbor- 
hood, the surgeon will be called upon to bring to a proper 
shape frames which have passed through all sorts of 
accidents, and it is better that he should do this work than 
entrust it to less competent hands. 

Proving the Strength of Lenses. — The focal strength 
of a convex lens may be directly measured by finding the 
distance at which it brings the sun's rays to a focus. To 
do this, the rays which have passed through the lens are 
simply caught upon a piece of paper, or other screen, the 
two being held in such relationship that the image of the 
sun formed on the screen is round. The screen is then to 
be moved back and forth until the point is found at which 
this image is smallest, and the distance of such point from 
the lens is the focal length of the lens. To learn the 
strength of the lens in diopters, we divide ioo centimeters 

70 



INSPECTION AND ADJUSTMENT OF SPECTACLES. 7 1 

(one meter) by the focal length expressed in centimeters, 
or 40 inches (about one meter) by the focal length expressed 
in inches. For instance, if we found the focus of the lens 
under examination to be distant 10 in., or 25 cm., from the 
lens, 40 in. divided by 10 in., or 100 cm. divided by 25 
cm., will alike give a quotient of 4, and the lens measured 
was, therefore, a + 4. D. 

The focal length of a concave lens may be similarly 
measured by combining it with a stronger convex lens and 
then measuring the strength of the resulting weaker con- 
vex. The strength of the original convex used being 
known, we have only to subtract from it the weak convex 
resultant to find the strength of the concave with which we 
are dealing. The focal length of convex and concave 
cylindrical lenses may be measured in the same way as the 
corresponding sphericals, it being only necessary to observe 
that the parallel rays of light after passing through a 
convex cylindrical lens are arranged in the form of a line 
at the focus of such lens ; not brought to a point, as is the 
case with convex sphericals. 

Phacometers. — Such methods as the one described 
above are, however, too tedious for ordinary use, though 
quite elaborate contrivances called phacometers have been 
devised on this principle. A lens measure constructed on 
an entirely different idea has lately appeared, the invention 
of Mr. J. T. Brayton, of Chicago. Fig. 30 show r s the size 
and appearance of the instrument, as well as the method of 
its use. Of the three steel pins which project from its top 
the two outer ones are fixed, while the central one moves 
up and down easily but is held up by a spring. On press- 
ing the surface of a spherical lens squarely against these 
points, the central one will be depressed until they all 
three touch the glass ; the curvature of the surface of the 



J2 



SPECTACLES AND EYEGLASSES. 



lens determining the amount of such depression. The 
motion being transferred through a rather simple mechan- 
ism to the hand upon the dial, this travels over a scale which 
shows in diopters and in inches the strength of the lens 
corresponding to the surface tested. The other surface is 
then to be explored in the same way. If the lens is bicon- 
vex or biconcave, the results of measuring each surface 

Fig. 30. 




separately are added together ; if periscopic, the less is 
deducted from the greater. When used upon a cylindrical 
surface the hand will stand at zero when the three points 
are in line with the axis of the cylinder. When the points 
are placed at right angles to the axis the strength of the 
cylinder is shown. 

Since this instrument indicates the refractive value of a 
lens from the curvature of its surfaces only, leaving out of 



INSPECTION AND ADJUSTMENT OF SPECTACLES. 73 

account the index of refraction of the material, it is evident 
that it can be accurate for only one variety of glass. As 
found in the shops it is adjusted for crown glass, and for 
lenses of this material it is quite accurate ; while its con- 
venience and low price as compared with other phaco- 
meters recommend it to favor. 

Neutralization of Spherical Lenses. — The method of 
determining the strength of spectacles which is of most 
general utility is the well-known one of neutralization. If 
a convex spherical lens be held about a foot from the eye, 
and any object, say that part of a window frame where a 
vertical and horizontal line cross, be viewed through it, any 
motion given the lens will result in an apparent motion in 
the opposite direction of the object sighted. That is ; if 
the lens is moved to the right, the object appears to move 
to the left; if the lens is raised, the object appears to sink. 
If the same maneuver be employed with a concave spherical 
glass, the object again appears to move, but this time in the 
same direction as the motion imparted to the lens. If the 
lens is moved to the right, the object appears to move to 
the right also. Here we have the readiest possible means 
of distinguishing between a convex and a concave lens. 
Moreover, one gets in this way an idea of the strength of a 
lens, as the stronger the lens the more rapid is the apparent 
motion of the object seen through it. 

If, continuing the experiment, the two lenses be placed 
together, with their curved surfaces in apposition, and a 
trial be made of the effect of moving them before an object, 
as was done previously with each lens singly, the object 
will appear: I, (if the concave lens is the stronger) to 
move in the same direction as the motion of the glass, but 
more slowly than before ; 2, (if the convex lens is the 
stronger) to move in the opposite direction to the motion 



74 



SPECTACLES AND EYEGLASSES. 



of the glass, but more slowly than before; 3, (if the lenses 
are of equal strength) to have no motion. Therefore, to find 
the strength of a spherical lens it is only necessary to com- 
bine it in this way with successive lenses of known strength 
and of the opposite sign until that one is found which 
neutralizes the apparent motion of objects seen through it. 
This lens is the measure of the strength of the one tested. 
This method is accurate within an eighth diopter, or less, 
for plano-convex and plano-concave lenses ; with bi-convex 
and bi-concave glasses it is only possible to neutralize the 



Fig. 31. 



Fig. 32. 





apparent motion near the center of the lens ; toward the 
edges motion will still be visible when the lenses are 
strong. 

Cylindrical lenses maybe recognized by viewing through 
them some object presenting a straight line, say the vertical 
line of a window sash. If the cylindrical lens be rotated 
about the visual axis, the portion of the vertical line seen 
through the glass will appear to be oblique, as compared 
with that seen above and below the glass (Fig. 31). This 
oblique displacement takes place in a direction contrary to 



INSPECTION AND ADJUSTMENT OF SPECTACLES. 75 

the rotary motion given the lens if the latter is convex, and 
in the same direction as the motion if the lens is concave. 
To ascertain the position of the axis of a cylindrical lens it 
should be rotated slowly in this manner until the line seen 
through it appears continuous with that above and below 
(Fig. 32). This line will then lie either in the axis or at 
ri^ht angles to it. To ascertain which of the latter is the 
case the effect of motion from side to side is to be tried. 
If the axis of the cylinder corresponds w r ith the vertical line 
looked at, motion from side to side produces apparent 
motion of the object; if, however, the axis lies at right 
angles to the vertical line no such motion results. In 
other words, in the direction of its axis a cylindrical lens 
acts as a piece of plain glass; across its axis it acts as a 
spherical lens of the same strength. The direction of the 
axis of a cylindrical lens having been ascertained, its 
strength may be determined by neutralizing it with a 
cylinder of the opposite sign, as was explained when speak- 
ing of spherical lenses. Care must be taken that the two 
lenses are so placed that their axes coincide. 

A Sphero-Cylindrical Lens is equal in refractive effect 
to two cylindrical lenses with their axes perpendicular to 
each other. Having found that axis across which motion 
is least rapid, we may neutralize the motion with a 
spherical lens, and holding these two together, proceed to 
neutralize the motion across the other axis just as if deal- 
ing with a simple cylinder. When our object is not to de- 
termine the strength of an unknown lens, but to see if the 
lenses of a pair of spectacles agree with the prescription 
previously written, we may, of course, shorten the above 
procedures by picking out from the test case the glass, or 
glasses, which will neutralize the spectacles if the latter are 
of the proper strength, and observing whether the appar- 
ent motion of objects ceases when they are held together. 



7 6 



SPECTACLES AND EYEGLASSES. 



Locating the Optical Center. — Every glass before 
being worn should be examined with regard to the posi- 
tion of the optical center of each lens and the distance of 
these from each other, as inaccuracy in this important par- 
ticular is not uncommon. Indeed, in the cheap spectacles 
which some persons unfortunately buy, proper centering is 
the exception. In grinding large numbers of lenses by 
machinery a certain number in each batch are, I believe, 
always found to be badly centered. These are not returned 

Fig. 33. 




to the wheel or the furnace by the thrifty manufacturer, but 
are graded as second class, or if very bad indeed as third 
class, and with those which will not pass inspection in other 
particulars go to make up the trash sold by peddlers. 

A simple way to find the location of the optical center is 
to hold the lens about a foot above the corner of a rectangu- 
lar card lying on the table. The corner seen through the 
lens will only appear complete and continuous with the rest 
of the card when its tip is opposite the optical center. . 

In Fig. 33, a represents a lens so held that its optical 



INSPECTION AND ADJUSTMENT OF SPECTACLES. 



77 



center is marked by the corner of the underlying card ; b 
is a lens improperly held. The center first found may be 
marked with a speck of ink, the center of the other spec- 
tacle glass found in the same way, and the distance between 
them measured. If care is taken to hold the glass exactly 
level and the eye directly over it this method will give 
results accurate enough for most purposes. 

The Apex of a Prism may be determined by viewing 
through the glass fine lines crossed at right angles, holding 
the prism so that its edge and supposed apex just touches 
one line at the point of intersection. When the real apex 
of the prism coincides with the intersection of the lines, the 



Fig. 34. 



Fig. 35. 





Method of Finding the Apex of a Prism. [After Maddox.) 



appearance presented is that shown in Fig. 34 ; when, how- 
ever, the apex is to one side of the point of intersection, 
the line seen through the prism appears broken, as in Fig. 
35. In this case the prism is to be rotated until the line 
appears continuous, when the point of intersection of the 
lines will mark the apex of the prism. 

The strength of a prism may be expressed in two ways ; 
either in degrees of the refracting angle, which is the angle 
forming the edge and separating the two refracting surfaces 
of the prism, or by means of some formula which denotes 
the power of the prism to turn a ray of light from its course. 
This power is usually expressed in degrees of the angle of 



yS SPECTACLES AND EYEGLASSES. 

deviation, which is the angle separating the course of a ray 
of light after having passed through the prism from that 
which it would have pursued had its course been unob- 
structed. The obvious advantage of the latter mode of 
expression, which gives directly the optical strength of the 
prism, over the former, which merely states the value of a 
physical angle from which the strength can be more or less 
accurately inferred, has called forth several suggestions for 
an improved method of numbering ophthalmological prisms. 
Dr. Edward Jackson has proposed, that in harmony with 
the mode of stating the value of angles which is commonly 
accepted in other departments of science, they be marked 
in degrees of their angles of deviation. With the idea of 
conforming their numeration to the dioptric system of 
numbering lenses, Mr. C. F. Prentice proposed to adopt as 
a unit that prism having the power necessary to produce 
one centimeter of deviation in the course of the ray after 
having passed through and the distance of one meter 
beyond the prism. Dr. S. M. Burnett proposes that this 
unit be called the prism diopter, and that the centimeter 
of deviation be measured upon a plane surface ; that is, 
upon a tangent of the arc whose radius is one meter Dr. 
W. S. Dennett prefers to call the unit a centrad, and to 
measure the deviation on the arc itself. Pending the general 
adoption of one of these proposals, it is sufficient for our 
purpose to note in regard to the two latter, that for oph- 
thalmological prisms, which are of necessity weak, the 
difference between measuring the amount of deviation on 
an arc of given radius and on a tangent of that arc is so 
slight as to be of no moment. Prism diopters and centrads, 
therefore, though in the scientific aspect of the subject they 
represent distinct ideas, may be regarded as of equal value 
when speaking of the strength of prismatic spectacle glasses. 



INSPECTION AND ADJUSTMENT OF SPECTACLES. Jg 

As the surgeon has a choice of three essentially different 
methods of numbering, so, also, he has at his command 
several modes of determining the strength of unknown 
prisms and may select that one which is simplest and 
involves least calculation for the numeration which he 
adopts. The refracting angle may be readily found by 
means of Table II, introduced when speaking of the pris- 
matic equivalent of decentered lenses. The situation of the 
optical center is to be marked upon a spherical lens of con- 
venient strength, and the prism to be tested superimposed. 
By viewing the corner of a card through these two glasses, 
as was directed in describing the method of finding the 
optical center, this center will be found to have been carried 
toward the base of the prism. The position of this apparent 
optical center is to be likewise marked upon the spherical 
lens, and its distance from the true one measured. In the 
left-hand column of Table II find the strength of the lens 
used, and on a level with this across the page the distance 
in millimeters between the true and apparent optical centers. 
At the head of the column in which this measurement is 
found will stand the strength of the prism with which the 
lens w r as combined, this strength being expressed in degrees 
of the refracting angle. For instance, if having combined 
an unknown prism w T ith a + 7- E). lens we find the apparent 
displacement of the optical center to be 4 mm., the table 
shows at a glance that the refracting angle of the prism 
tested had a value of 3 . 

The refracting angle may be directly measured by 
adapting the legs of a pair of compasses to the two re- 
fracting surfaces and then laying the compasses on an 
ordinary protractor. Various other mechanical contri- 
vances have been invented for effecting the same purpose, 
one of the best of which is represented in Fig. 36. It con- 



8o 



SPECTACLES AND EYEGLASSES. 



sists of a bed-plate A, upon the front of which is affixed a 
degree-circle G, and hinged to A at H is the upper plate B 
held up by the spring M, not plainly shown because it is 
under B. The upright face-plate C stands at right angles 
to B. On top of C is the degree-circle E. The index- 
finger F with the lower part D D' is made of steel and 



Fig. 36. 




....AJ 



pivoted at P to swing easily over any portion of the dial 
plate. In measuring a prism, the position of the index 
finger F will be governed by the difference of the thick- 
ness of the lens at the points D and D', and the degrees of 
the refracting angle of the prism will be indicated on the 
scale E by the pointer F. 

The surgeon is, however, very little concerned with the 



INSPECTION AND ADJUSTMENT OF SPECTACLES. 8 1 

refracting angles of the prisms, except as they are the basis 
of the old system of numbering, which will doubtless soon 
be superseded by one in which the number of the prism 
shall express in one of the ways mentioned above the power 
which that prism possesses of causing deviation in a ray of 
light. One of the simplest and most convenient devices for 
measuring this power is that suggested by Dr. Maddox. 
It consists of a strip of cardboard suspended horizontally on 
the wall on a level with the eyes of the observer. The 
upper border of the card (Fig. 37) is marked from right to 
left with a scale of degrees, or rather tangents of degrees, 
proper to the distance at which the prism is to be held from 

Fig. 37. 




the card. In Table IV is given the distance from the right- 
hand border of the card of the mark for each degree of 
deviating angle. With the help of this table one may 
readily construct the scale, using column A if he elect to 
work at 6 feet, or column B if a 2-meter range be preferred. 
To practice this method of prismetry, the glass to be 
tested is held at the proper distance from the card, its apex 
to the left, and its upper border just below the figures of the 
scale, as in Fig 37. The observer's eye being placed behind 
the prism, the right vertical border of the card appears dis- 
placed toward the observer's left and points upward to the 
number expressing the strength of the prism in degrees of 
the angle of deviation. During this maneuver care must 
be taken that the prism is held at precisely the distance 
7 



82 



SPECTACLES AND EYEGLASSES. 



from the card for which the scale of the latter is arranged ; 
also that the apex of the prism points exactly to the left. 
This latter requirement may be secured by rotating the 
prism until the line of the bottom of the card appears un- 
broken, as at a, in Fig. 37. In adapting this method ol 
prismetry to centrads or prism diopters, the scale at the 
top of the card should simply be laid off in centimeters, and 
the prism be held at the distance of one meter. Each cen- 

table IV.* 



For 


Marking a 


Card in Tangents of Degrees at 6 Feet 




(Column A) ; or 2 Meters (Column B) 






A 


B 




A 


B 


1° 


1.25 in. 


3.49 cm. 


9° 


11. 4 in. 


31.29 cm. 


2° 


2.5 « 


6.98 " 


IO° 


12.6 " 


34-73 " 


3° 


3-7 " 


IO.467 " 


ii° 


14.0 " 


38.16 « 


4° 


5.0 « 


13 95 " 


12° 


15-3 " 


41.58 - 


5° 


6.3 - 


1743 " 


13° 


166 " 


44-99 " 


6° 


7.57 « 


20.9 " 


14 


17.9 " 


48.38 - 


7° 


8.84 " 


24 37 " 


i5° 


19.3 " 


51.76 « 


8° 


10.12 " 


2783 - 


1 6° 


20.64 " 


55-13 " 



timeter that the right border of the card is apparently 
moved to the left on viewing it through the prism, will then 
represent one centrad, or one prism diopter. 

Scratches, specks, bubbles, flaws, etc., in the glass 
will hardly escape detection if they are carefully looked 
for while the lens is held in different lights. Placing the 
glass against a dark background and allowing a bright 
light to fall obliquely upon it will perhaps bring them out 
as plainly as any other maneuver. 



* From Maddox. " The Clinical Use of Prisms.' 1 



INSPECTION AND ADJUSTMENT OF SPECTACLES. 83 

Irregularity of the Surface may be discovered by 
reflecting from that surface any object having regular out- 
lines. The observer should stand facing a window, holding 
the lens against a dark background in his left hand, and 
pass a straight-edged piece of paper held in his right hand 
between his eyes and the lens. Two images of the paper 
will be reflected from the lens; one formed by each surface. 
Any irregularity of these surfaces will make the images 
appear broken, or with wavy outlines. 

Adjusting Spectacle Frames. — It requires some little 
practice to enable one to tell at a glance just where such 
an irregularly shaped object as a spectacle frame has been 
wrongly bent ; having found the error it is a more simple 

Fig. 38. 



matter to correct it. For the latter purpose two small 
pliers are required. They should have narrow, but strong 
jaws ; round in one pair, and square in the other. As 
found in the shops, the grasping surfaces of the jaws are 
generally roughened, but should be smoothed off with 
a file, lest they scar the gold when in use. A small, stout 
screw-driver with a point suited to the screws of spectacles 
will also be necessary. 

Eye-wires are generally of such light material as to take 
their shape from the contained glass, and are therefore, not 
liable to become misshapen. Sometimes the long axis of an 
oval eye gets rotated within the eye-wire (Fig. 38), so that 



SPECTACLES AND EYEGLASSES. 



it no longer stands squarely across the face. By loosening 
the screw it can readily be re-adjusted. Abnormal crooked- 
ness about the bridge is best disclosed by placing a straight 



Fig. 39. 




edge (indicated by the line S E in Figs. 38, 39, 41, 42, and 
43) in such a position as to enable one to compare the two 
sides of the frame. If the bridge is bent at its junction 



Fig. 40. 




with the eye-wire a rotation results, looking very much 
like that just mentioned but dependent upon an entirely 
different fault (Fig. 39). It is readily corrected with pliers, 



or fingers. 



INSPECTION AND ADJUSTMENT OF SPECTACLES. 85 

Fig. 41. 




Fig. 42. 



fe^4U^ 




Fig. 43. 



^ 



86 SPECTACLES AND EYEGLASSES. 

The planes of the glasses may cross each other (Fig. 40), 
in consequence of a twist in almost any part of the bridge, 
though the trouble is, usually, that the angle of the bridge 
at a is not of the same size as its fellow of the opposite 
side. The bridge is inclined, as shown in the cut, more to 
one glass than to the other. It requires application to the 
patient's face to determine which is the proper inclination, 
and in order that the glasses may be equalized at this and 
not at the improper one. 

In Fig. 41, the bend is at the junction of the eye-wire 
with the bridge ; rendering corresponding angles of the two 
sides of the frame unequal. The diagram shows the 
change necessary to correct the trouble. A similar fault 
is shown in Fig. 42. This appears at first sight to be 
just like the last ; it is, however, a neighboring angle of 
the bridge which needs equalizing with its fellow. 

In the frame represented in Fig. 43 the glasses lie in the 
same plane, but one of them is nearer the center of the 
bridge than the other, due to the fact that of the angles of 
the bridge which can be seen by viewing the frame in this 
position, the two which lie on one side of the curved portion 
are too much open, while the two on the other side are too 
little so. Of course, the bridge may be misshapen in any 
portion of its extent, but the illustrations given are sufficient 
to show the sort of faults one may expect. 

Having rectified all want of symmetry in the " front," 
the defects in the fit of the temples can best be corrected 
by trying the frames on the patient's face. If on doing so 
it is found that their temples cut into the temples of the 
wearer, instead of just touching the skin as they should do, 
the trouble is obviously that the distance between the tem- 
ples is too small, and they must be bent out at the hinges, 
so as to throw them, when open, further apart. This is 



INSPECTION AND ADJUSTMENT OF SPECTACLES. 87 

done with the square-jawed pliers, seizing the wire close 
up to the hinge. When the opposite condition pertains, 
that is, when the distance between the temples is too great, 
leaving a space between each wire and the side of the 
wearer's head, they require to be bent in. To do this, take 
the end of each side in turn in the square-jawed pliers, in 
such a way that the edge of one jaw shall be in contact with 
the temple as close to the hinge as possible and the latter 
be held rigidly open. The temple may then be pressed in 
with the fingers, and will bend at the point where it is pressed 
against the edge of the pliers. If the latter are rightly 
placed this does not make an angle in the wire forming the 
temple, but simply alters the angle already formed at A in 
Fig. 43, by the expansion of the end of the temple to help 
form the hinge. Care must be taken that one temple is 
not bent out more than the other, or, as is apt to be the 
case, become so during use. When this happens the effect 
is quite different from what might be expected. The glass 
on the same side as the temple the more bent out will be 
brought closer to the eye, while its fellow will be carried 
further forward and the bridge will ride obliquely across 
the nose. To remedy this it is only necessary to equalize 
the divergence of the temples. 

The curve of hook temples given them by the maker 
will rarely be found to fit comfortably behind the ear. As 
has been pointed out by Dr. Charles H. Thomas, the proper 
form for hook temples is a straight line from the hinge to 
the top of the ear, where a sharp curve should join this part 
of the temple to the easy curve which corresponds to the 
back of the ear (Fig. 40). Where the curve given the hook 
is too wide and is extended upon that part of the wire rest- 
ing against the patient's temple, as shown by the dotted 
line in Fig. 44, there is a constant tendency of the specta- 



88 SPECTACLES AND EYEGLASSES. 

cles to slide forward. The wire, moreover, touches the 
back of the ear for a short distance only, where its pressure 
is further increased by the fact of the whole temple being 
put upon the stretch and acting as a spring. Especially at 
first should the frames not fit too tightly, as the skin is then 
more easily irritated by the wire than when it becomes 
accustomed to its presence. 

In persons whose ears stand out far from the head a 
certain ridge upon the cartilage of the ear is thrown into 
prominence. Since the curve of a hook temple is a regular 
one, it will rest upon this ridge and be very uncomfortable ; 
indeed it may cut through the skin and into the cartilage. 

Fig. 44. 




Under such circumstances the portion of the wire which is 
behind the ear should be made to follow every depression 
and elevation of the surface with w T hich it is in contact ; as 
it should in any case w r here the auricle is deformed or 
irregular in any way. 

If one lens stands higher upon the face than the other, 
so that the patient looks through the upper part of one 
glass and the low 7 er part of the other, it will be found that 
the temple on the side w T hich stands the higher is turned 
down more than its fellow. It should be raised, or more 
frequently, its fellow should be lowered. The fault may 
lie in the bridge, as shown in Fig. 40, or in the end piece, 
or in the temple itself. In the first instance, bringing the 



INSPECTION AND ADJUSTMENT OF SPECTACLES. 89 

lenses into the same plane removes the difficulty ; in the 
second, take the end piece in the round-jawed pliers; the 
jaws being applied to its edges close up to the eye wire. 
Holding these pliers in the left hand, apply the square 
jaws of the other pliers to the surfaces of the end piece ; 
when, by twisting the latter about its long axis, the temple 
may be turned down to any desired extent. Thus, the 
temple is not bent at all, but the end piece between the 
hinge and the eye wire. Nearly the same effect may be 
produced by bending the wire of the temple close up to the 
hinge. As was remarked before, in speaking of the facing 

Fig. 45. 




of the glasses, the effect of turning down both temples is 
not to make both lenses stand higher upon the face, but to 
make the glasses face more downward. 

Sometimes when the glasses do not sit properly the 
trouble will be found to be not in the frames but in the 
wearer. A considerable amount of asymmetry of the two 
sides of the face is not uncommon. One ear or one eye 
may be higher than its fellow ; either of which conditions 
will make the glasses seem awry, and render necessary a 
compensating asymmetry of their frames. 

Adjustment of Eyeglasses. — The starting-point in 
adjusting eyeglasses is at the nose pieces^ whose free sur- 



gO SPECTACLES AND EYEGLASSES. 

faces should be made to conform accurately to the bones of 
the nose by which they are supported When received 
from the maker they are generally curved, presenting a 
convexity toward the nose. As the bones of the sides of 
the nose at the point where the guards are to rest are 
usually more or less convex also, the bearing obtained is 
a most insecure and uncomfortable one, as a glance at Fig. 
45 will show. In Fig. 46 this glass is shown with its nose 
pieces properly adapted to the sides of the nose. Any con- 
formation may be required, but that shown in Fig. 46 is 
the one most frequently needed. These changes in the 

Fig. 46. 




shape of the nose pieces are readily effected by means of 
the square-jawed pliers, especially if the so-called shell 
guards are used. The celluloid of which they are really 
made is, together with its gold backing, readily moulded 
into whatever shape is desired. When the guards are of 
cork, care must be taken that they are not scarred and 
broken by the pliers, and a special tool with a longitudinal 
groove in the jaws for grasping the sides of the nose pieces 
is here of service. 

Having conformed the nose pieces to their bony support, 
the tension of the spring by which they are pressed against 
the sides of the nose is to be regulated, the object being to 



INSPECTION AND ADJUSTMENT OF SPECTACLES. 



91 



have just sufficient force exerted to keep the guards securely 
in place. If the latter are properly fitted the amount of 
pressure necessary is not great. Though this pressure 
should be evenly distributed over the surfaces of the nose 
pieces, want of firmness in the " pinch " of their tops is 
particularly fatal, as the lower ends then become the prin- 
cipal support of the weight of the glasses, rendering them 
prone to topple forward and fall. To increase the tension 
of the spring, and consequently the pinch of the frames, 

Fig. 47. 

A 




the curve of the spring included between the lines at A, in 
Fig. 47, should be made more arched and rounded. Con- 
versely, the force of the spring is lessened by flattening this 
arch. Any alteration in the shape of the spring, however, 
while it does not, of course, change the shape of the nose 
pieces, does change the angle at which they are inclined to 
each other. For instance, if the spring be made more 
arched, the nose pieces are brought nearer together, but 
the bottoms are especially approached toward each other. 
When the spring is flattened the bottoms of the nose pieces 



92 SPECTACLES AND EYEGLASSES. 

are thrown proportionately farther apart than the tops. It 
follows that with each adjustment of the tension of the 
spring the inclination of the nose pieces must be rectified. 
This is easily accomplished by twisting the " foot " or sup- 
port of the nose piece at b in Fig. 47. It will be readily 
seen, moreover, that the nose pieces must incline equally 
to a vertical plane passing through the center of the nose ; 
otherwise the glasses will stand awry. 

When the points mentioned have been properly ad- 
justed, the long axis of one or both glasses may fail to 
stand squarely across the face as it should do. The remedy 
lies in an appropriate bend of the spring at the point c 
(Fig. 47). This also requires a slight re-adjustment of the 
inclination of the nose pieces to each other. 

The distance between the centers of eyeglasses is deter- 
mined (the distance between the nose pieces when in use 
being a fixed quantity) by the distance of the nose piece on 
each side from the center of the corresponding eye. The 
intercentral measurement may therefore be varied by vary- 
ing the size of the eye used, and by altering the distance 
of the nose pieces from the edges of the lenses by an 
appropriate bend of the foot b, (Fig. 47). The distance of the 
glasses from the eye is controlled by the length of the foot 
b, and in the better grades of goods this part is made in 
two or three lengths. 

The Care of Spectacles. — Spectacle frames will last 
longer and perform their function better if the wearer is 
instructed to exercise care in handling them. In putting 
them on and off, the hooks should be lifted from or into 
their position behind the ears ; both hands being used, so 
as to avoid straining the temples widely apart or otherwise 
bending them. They should be folded together as little as 
possible, and when not in use should be laid in a safe place, 



INSPECTION AND ADJUSTMENT OF SPECTACLES. 93 

open, and resting on the edges of the lenses, to avoid scratch- 
ing the surfaces of the latter. For cleansing them nothing is 
better than a piece of clean old linen, or, if very much soiled, 
a little ammonia and water maybe used, except on cemented 
bifocal glasses. While cleansing, the frame should be 
grasped by the end piece and not by the bridge, and in 
replacing the glasses on the eyes care should be taken not 
to crush them against the lashes and thus soil the refracting 
surfaces at once. When cylindrical or prismatic glasses are 
worn, patients may return after a time with the statement 
that the spectacles are unsatisfactory, when the trouble will 
frequently be found to be due to bending of the frame ; or 
a lens may have fallen out and been replaced upside 
down, or with the wrong edge inward. It is well to have 
such persons report periodically to have their glasses 
re-adjusted. 



NDEX. 



Adjustment of eyeglasses, 89 

of spectacles, 83 
Airy, discoverer of astigmatism, 23 
Alhazen, 19 
Ancient glass, 17 
Angle, deviating, of a prism, 78, 81 

refracting, 77, 79 
Apex of a prism, finding the, 77 
Assyrians, knowledge of lenses 

among, 18 
Astigmatism, discovery of, 23 
Asymmetry of the face, 89 

Bar spring eyeglasses, 42 
Bifocal glasses, 37 

invention of, 23 
varieties of, 39 
Brewster, Sir David, 18, 23 
Bridge, width of base of, 67 

relation of top of to plane of 

glasses, 52, 66 
height of, 65 
Bridges, manufacture of, 34 
varieties of, 36 

Care of spectacles, 92 
Cemented bifocals, 39 
Centering and decentering, 44 

normal lateral, 49 

normal vertical, 50 

of spectacles for constant use, 49 
near work, 49, 51 
Centrad, 78 

Chemical composition of glass, 29 
Component parts of spectacles, 27 
Conformation of nose pieces, 90 
Crown glass, 29 
Cylinder, finding the axis of, 74 

Date of invention of spectacles, 20 



Decentered lenses, 45 

prismatic effect of, 46 
Deviating angle of a prism, 78, 81 
Di Spina, Alessandro, 20 
Discovery of astigmatism, 23 
Distance between the pupils, 49, 61 
Distance between temples, 86 

of the glasses from the eyes, 51 

Emerald used by Nero, 18 
Epicanthus, eyeglasses for, 43 
Eyeglasses, advantages and disadvan- 
vantages of, 26 

inspection and adjustment of, 70, 

89 

prescription of, 69 

varieties of, 40 
Extra front, 40 
Eye wires, manufacture of, 34 

Face, asymmetry of, 64, 68, 89 

Facing of spectacles, 53 

Focal length of lenses, 70 

Frames (see spectacle frames) 

Frameless spectacles, 34 

Franklin, inventor of bifocal glasses, 

Franklin glasses, 37 

Geometrical center, 44 

Glass, chemical composition of, 29 

ancient, 17 
Ground bifocals, 39 

Height of bridge, 65 
Hook temples, 35, 87 

Inspection and adjustment of specta- 
cles, 70 
Interpupillary distance, 49, 59, 61 
Introduction, 17 



95 



9 6 



INDEX. 



Invention of spectacles, 20 
Irregularity of surface of lenses, 

Kepler, Johann, 22 



83 



Lateral centering, 49 
Lathe for grinding lenses, 30 
Lens, oldest known, 18 
Lenses, decentered, 45 

finding focal length of, 70 

known to the ancients, 18 

material of, 28 

method of grinding, 30 

neutralization of spherical, 73 
cylindrical, 74 
sphero-cylindrical, 75 

proving the strength of, 70 

toric, 33, 57 

tilted, 52 
Locating the optical center, 76 
Lorgnettes, 26 

Maddox pupil localizer, 63 
Marking of gold spectacle frames, 27 
Material of lenses, 28 
Material of spectacle frames, 26 

Natural position for spectacle bridge, 

5o 
Nero, concave jewel used by, 18 
Neutralization of spherical lenses, 73 
cylindrical lenses, 74 
sphero-cylindrical lenses, 75 
Normal position of spectacles, 44 
Nose pieces, conformation of, 90 
Numeration of prisms, 78 

Offset guard, 42 
Oldest known lens, 18 
Optician's lathe, 30 
Optical center, 44 

locating the, 76 

Pebble spectacles, 29 

Periscopic glasses, 32, 56 

Pince-nez (see eyeglasses) 

Phacometers, 71 

Plane of the glasses, relation to the 

visual axis, 52 
Prism diopter, 78 



Prism, finding the apex of, 77 
deviating angle of, 78, 81 
refracting angle of, 77, 79 

Prisms, numeration of, 78 

Prismatic effect of decentering, 46, 48 

Prismetry, 77 

Prescription blank for spectacles, 61 

Prescription of eyeglasses, 69 

Prescription of frames, 59 

Proving the strength of lenses, 70 

Principles of spectacle fitting, 44 

Principal axis, 44 

Pupil localizer, 63 

Pupilometer, 65 

Quizzing glasses, 26 

Refracting angle of a prism, 77, 79 

Rigid frame eyeglasses, 42 

Rock crystal, 18, 29 

Romans, knowledge of lenses among, 

18 
Rule for measuring frames, 59 

Saddle bridge, 36 

Salvinus Armatus, 20 

Scratches, specks, flaws, etc., in glass, 

82 
Spectacle eyes, sizes of, 37 
shapes of, 37 
fitting, principles of, 44 
frames, adjustment of, 83 
material of, 26 
marking of gold, 27 
prescription of, 59 
rule for measuring, 59 
Spectacles, component parts of, 27 
bifocal, 37 
care of, 92 

date of invention of, 20 
early references to, 20, 21 
for cosmetic effect, 43 
invention of bifocal, 23 
inspection and adjustment of, 

70 
frameless, 34 
facing of, 53 
patterns of, 34 
pebble, 29 
periscopic, 32, 56 



INDEX. 



97 



St. Jerome's eyeglasses, 21 
Surface, irregularity of, 83 

Temples, distance between, 86 

manufacture of, 34 

varieties of, 35 
Tilted lenses, 52 
" Tool" for grinding spherical lenses, 

3° 
Tools for adjusting frames, S3 



Toric lenses, 33, 57 

Transparent glass found in Nineveh, 

f7 

Trial frames, 64, 68 

Vertical centering, 50 
Visual axis, relation of plane of the 
glasses to, 52 

Width of base of bridge, 67 



CATALOGUE No. 7. 



MARCH, 1892. 



A CATALOGUE 

OF 

Books for Students. 



INCLUDING THE 



? QUIZ-COMPENDS ? 





CONTENTS. 




PAGE 


PAGE 


New Series of Manuals 


, 2,3,4,5 


Obstetrics io 


Anatomy, 


. . 6 


Pathology, Histology, . . n 


Biology, 


. ii 


Pharmacy, . . . .12 


Chemistry, . 


. 6 


Physical Diagnosis, . .11 


Children's Diseases, . 


• 7 


Physiology, . . . .11 


Dentistry, 


, 8 


Practice of Medicine, . 11, 12 


Dictionaries, 


8, 16 


Prescription Books, . . 12 


Eye Diseases, 
Electricity, . 


• 9 


?Quiz-Compends ? . 14,15 


• 9 


Skin Diseases, . . .12 


Gynaecology, 


. io 


Surgery and Bandaging, . 13 


Hygiene, 


• 9 


Therapeutics, . . .9 


Materia Medica, . 


• 9 


Urine and Urinary Organs, 13 


Medical Jurisprudence 


. IO 


Venereal Diseases, . . 13 



PUBLISHED BY 



P. BLAKISTON, SON & CO., 

Medical Booksellers, Importers and Publishers. 

LARGE STOCK OF ALL STUDENTS' BOOKS, AT 
THE LOWEST PRICES. 

1012 Walnut Street, Philadelphia. 



*** For sale by all Booksellers, or any book will be sent by mail, 
postpaid, upon receipt of price. Catalogues of books on all branches 
of Medicine, Dentistry, Pharmacy, etc., supplied upon application. 



Just Ready 
Price 10 cents 



3000 Questions on Medical Subjects. 



"An excellent Series of Manuals." — Archives of Gynecology. 

A NEW SERIES OF 

STUDENTS' MANUALS 

On the various Branches of Medicine and Surgery. 

Can be used by Students of any College. 

Price of each, Handsome Cloth, $3.00. Full Leather, $3.50. 

The object of this series is to furnish good manuals 
for the medical student, that will strike the medium 
between the compend on one hand and the prolix text- 
book on the other — to contain all that is necessary for 
the student, without embarrassing him with a flood of 
theory and involved statements. They have been pre- 
pared by well-known men, who have had large experience 
as teachers and writers, and who are, therefore, well 
informed as to the needs of the student. 

Their mechanical execution is of the best — good type 
and paper, handsomely illustrated whenever illustrations ■ 
are of use, and strongly bound in uniform style. 

Each book is sold separately at a remarkably low 
price, and the immediate success of several of the 
volumes shows that the series has met with popular 
favor. 

No. 1. SURGERY. 318 Illustrations. 

Third Edition. 

A Manual of the Practice of Surgery. By Wm. J. 

Walsham, M.D., Asst. Surg, to, and Demonstrator of 

Surg, in, St. Bartholomew's Hospital, London, etc. 

318 Illustrations. 

Presents the introductory facts in Surgery in clear, precise 
language, and contains all the latest advances in Pathology, 
Antiseptics, etc. 

" It aims to occupy a position midway between the pretentious 
manual and the cumbersome System of Surgery, and its general 
character may be summed up in one word — practical." — The Medi- 
cal Bulletin. 

"Walsham, besides being an excellent surgeon, is a teacher in 
its best sense, and having had very great experience in the 
preparation of candidates for examination, and their subsequent 
professional career, may be relied upon to have carried out his 
work successfully. Without following out in detail his arrange- 
ment, which is excellent, we can at once say that his book is an 
embodiment of modern ideas neatly strung together, with an amount 
of careful organization well suited to the candidate, and, indeed, to 
the practitioner." — British Medical Journal. 

Price of each Book, Cloth, $3.00 ; Leather, $3.50. 



THE NEW SERIES OF MANUALS. 



No. 2. DISEASES OF WOMEN. 150 Illus. 

NEW EDITION. 

The Diseases of Women. Including Diseases of the 
Bladder and Urethra. By Dr. F. Winckel, Professor 
of Gynaecology and Director of the Royal ' University 
Clinic for Women, in Munich. Second Edition. Re- 
vised and Edited by Theophilus Parvin, m.d., 
Professor of Obstetrics and Diseases of Women and 
Children in Jefferson Medical College. 150 Engrav- 
ings, most of which are original. 
" The book will be a valuable one to physicians, and a safe and 

satisfactory one to put into the hands of students. It is issued in a 

neat and attractive form, and at a very reasonable price." — Boston 

Medical and Surgical Journal. 

No. 3. OBSTETRICS. 227 Illustrations. 
A Manual of Midwifery. By Alfred Lewis Galabin, 
M.A., M.D., Obstetric Physician and Lecturer on Mid- 
wifery and the Diseases of Women at Guy's Hospital, 
London; Examiner in Midwifery to the Conjoint 
Examining Board of England, etc. With 227 Illus. 
" This manual is one we can strongly recommend to all who 
desire to study the science as well as the practice of midwifery. 
Students at the present time not only are expected to know the 
principles of diagnosis, and the treatment of the various emergen- 
cies and complications that occur in the practice of midwifery, but 
find that the tendency is for examiners to ask more questions 
relating to the science of the subject than was the custom a few 
years ago. * * * The general standard of the manual is high ; 
and wherever the science and practice of midwifery are well taught 
it will be regarded as one of the most important text-books on the 
subject.' 1 — London Practitioner . 

No. 4. PHYSIOLOGY. Fifth Edition. 

321 ILLUSTRATIONS AND A GLOSSARY. 

A Manual of Physiology. By Gerald F. Yeo, m.d., 
f.r.cs., Professor of Physiology in King's College, 
London. 321 Illustrations and a Glossary of Terms. 
Fifth American from last English Edition, revised and 
improved. 758 pages. 

This volume was specially prepared to furnish students with a 
new text-book of Physiology, elementary so far as to avoid theories 
which have not borne the test of time and such details of methods 
as are unnecessary for students in our medical colleges. 

" The brief examination I have given it was so favorable that I 
placed it in the list of text-books recommended in the circular of the 
University Medical College." — Prof. Lewis A. Sti?nson, m.d., 
57 East 33d Street, New York. 

Price of each Book, Cloth, $3.00; Leather, $3.50. 



THE NEW SERIES OF MANUALS. 



No. 5. DISEASES OP CHILDREN. 

SECOND EDITION. 

A Manual. By J. F. Goodhart, m.d., Phys. to the 
Evelina Hospital for Children; Asst. Phys. to 
Guy's Hospital, London. Second American Edition. 
Edited and Rearranged by Louis Starr, m.d., Clinical 
Prof, of Dis. of Children in the Hospital of the Univ. 
of Pennsylvania, and Physician to the Children's Hos- 
pital, Phila. Containing many new Prescriptions, a list 
of over 50 Formulae, conforming to the U. S. Pharma- 
copoeia, and Directions for making Artificial Human 
Milk, for the Artificial Digestion of Milk, etc. Illus. 

" The merits of the book are many. Aside from the praiseworthy 
work of the printer and binder, which gives us a print and page 
that delights the eye, there is the added charm of a style of writ- 
ing that is not wearisome, that makes its statements clearly and 
forcibly, and that knows when to stop when it has said enough. 
The insertion of typical temperature charts certainly enhances the 
value of the book. It is rare, too, to find in any text-book so many 
topics treated of. All the rarer and out-of-the-way diseases are 
given consideration. This we commend. It makes the work 
valuable." — Archives 0/ Pedriatics , July , i8go. 

" The author has avoided the not uncommon error of writing a 
book on general medicine and labeling it ' Diseases of Children,' 
but has steadily kept in view the diseases which seemed to be 
incidental to childhood, or such points in disease as appear to be so 
peculiar to or pronounced in children as to justify insistence upon 
them. * * * A safe and reliable guide, and in many ways 
admirably adapted to the wants of the student and practitioner." — 
American Journal of Meaical Science. 

" Thoroughly individual, original and earnest, the work evi- 
dently of a close observer and an independent thinker, this book, 
though small, as a handbook or compendium is by no means made 
up of bare outlines or standard facts." — The Therapeutic Ga- 
zette, 

" As it is said of some men, so it might be said of some books, 
that they are 'born to greatness/ This new volume has, we 
believe, a mission, particularly in the hands of the younger 
members of the profession. In these days of prolixity in medical 
literature, it is refreshing to meet with an author who knows both 
what to say and when he has said it. The work of Dr. Goodhart 
(admirably conformed, by Dr. Starr, to meet American require- 
ments) is the nearest approach to clinical teaching without the 
actual presence of clinical material that we have yet seen." — New 
York Medical Record. 

Price of each Book, Cloth, $3.00 ; Leather, $3.50. 



THE NEW SERIES OF MANUALS. 



No. 6. PRACTICAL THERAPEUTICS. 

FOURTH EDITION, WITH AN INDEX OF DISEASES. 

Practical Therapeutics, considered with reference to 
Articles of the Materia Medica. Containing, also, an 
Index of Diseases, with a list of the Medicines 
applicable as Remedies. By Edward John Waring, 
m.d., f.r.c.p. Fourth Edition. Rewritten and Re- 
vised by Dudley W. Buxton, m.d., Asst. to the Prof, 
of Medicine at University College Hospital. 

" We wish a copy could be put in the hands of every Student or 
Practitioner in the country. In our estimation, it is the best book 
of the kind ever written." — N. Y. Medical Journal. 

" Dr. Waring's Therapeutics has long been known as one of the 
most thorough and valuable of medical works. The amount of 
actual intellectual labor it represents is immense. . . . An in- 
dex of diseases, with the remedies appropriate for their treatment, 
closes the volume." — Boston Medical and Sicrgical Reporter. 

11 The plan of this work is an admirable one, and one well calcu- 
lated to meet the wants of busy practitioners. There is a remark- 
able amount of information, accompanied with judicious comments, 
imparted in a concise yet agreeable style." — Medical Record. 

No. 7. MEDICAL JURISPRUDENCE AND 
TOXICOLOGY. 

THIRD REVISED EDITION. 

By John J. Reese, m.d., Professor of Medical Jurispru- 
dence and Toxicology in the University of Pennsyl- 
vania ; President of the Medical Jurisprudence Society 
of Phila. ; Third Edition, Revised and Enlarged. 

" This admirable text-book." — Amer.Jour. of Med. Sciences. 

u We lay this volume aside, after a careful perusal of its pages, 
with the profound impression that it should be in the hands of every 

doctor and lawyer. It fully meets the wants of all students 

He has succeeded in admirably condensing into a handy volume all 
the essential points." — Cincinnati Lancet and Clinic. 

" The book before us will, we think, be found to answer the ex- 
pectations of the student or practitioner seeking a manual of juris- 
prudence, and the call for a second edition is a flattering testimony 
to the value of the author's present effort. The medical portion 
of this volume seems to be uniformly excellent, leaving little for 
adverse criticism. The information on the subject matter treated 
has been carefully compiled, in accordance with recent knowledge. 
The toxicological portion appears specially excellent. Of that por- 
tion of the work treating of the legal relations of the practitioner 
and medical witness, we can express a generally favorable ver- 
dict." — Physician and Surgeon, Ann Arbor, Mich. 

Price of each Book, Cloth, $3,00; Leather, $3.50. 



6 STUDENTS' TEXT-BOOKS AND MANUALS. 

ANATOMY. 

Macalister's Human Anatomy. 816 Illustrations. A new 

Text-book for Students and Practitioners, Systematic and Topo- 
graphical, including the Embryology, Histology and Morphology 
of Man. With special reference to the requirements of 
Practical Surgery and Medicine. With 816 Illustrations, 
400 of which are original. Octavo. Cloth, 7.50; Leather, 8.50 
Ballou's Veterinary Anatomy and Physiology. Illustrated. 
By Wm. R. Ballou, m.d., Professor of Equine Anatomy at New 
York College of Veterinary Surgeons. 29 graphic Illustrations. 
i2mo. Cloth, 1. 00; Interleaved for notes, 1.25 

Holden's Anatomy. A manual of Dissection of the Human 
Body. Fifth Edition. Enlarged, with Marginal References and 
over 200 Illustrations. Octavo. 

Bound in Oilcloth, for the Dissecting Room, $4.50. 
" No student of Anatomy can take up this book without being 
pleased and instructed. Its Diagrams are original, striking and 
suggestive, giving more at a glance than pages of text description. 
* * * The text matches the illustrations in directness of prac- 
tical application and clearness of detail/' — New York Medical 
Record. 

Holden's Human Osteology. Comprising a Description of the 
Bones, with Colored Delineations of the Attachments of the 
Muscles. The General and Microscopical Structure of Bone and 
its Development. With Lithographic Plates and Numerous Illus- 
trations. Seventh Edition. 8vo. Cloth, 6.00 

Holden's Landmarks, Medical and Surgical. 4th ed. Clo., 1.25 

Heath's Practical Anatomy. Sixth London Edition. 24 Col- 
ored Plates, and nearly 300 other Illustrations. Cloth, 5.00 

Potter's Compend of Anatomy. Fifth Edition. Enlarged. 
16 Lithographic Plates. 117 Illustrations. See Page 14. 

Cloth, 1. 00; Interleaved for Notes, 1.25 

CHEMISTRY. 

Bartley's Medical Chemistry. Second Edition. A text-book 
prepared specially for Medical, Pharmaceutical and Dental Stu- 
dents. With 50 Illustrations, Plate of Absorption Spectra and 
Glossary of Chemical Terms. Revised and Enlarged. Cloth, 2.50 

Trimble. Practical and Analytical Chemistry. A Course in 
Chemical Analysis, by Henry Trimble, Prof, of Analytical Chem- 
istry in the Phila. College of Pharmacy. Illustrated. Fourth 
Edition, Enlarged. 8vo. Cloth, 1.50 

J9&* See pages 2 to 5 for list 0/ Students' Manuals. 



STUDENTS' TEXT-BOOKS AND MANUALS. 7 

Chemistry : — Continued. 

Bloxam's Chemistry, Inorganic and Organic, with Experiments. 
Seventh Edition. Enlarged and Rewritten. 281 Illustrations. 

Cloth, 4.50; Leather, 5.50 

Richter's Inorganic Chemistry. A text-book for Students. 
Third American, from Fifth German Edition. Translated by 
Prof. Edgar F. Smith, ph.d. 89 Wood Engravings and Colored 
Plate of Spectra. Cloth, 2.00 

Richter's Organic Chemistry, or Chemistry of the Carbon 
Compounds. Illustrated. Second Edition. Cloth, 4.50 

Symonds. Manual of Chemistry, for the special use of Medi- 
cal Students. By Brandreth Symonds, a.m., m.d., Asst. 
Physician Roosevelt Hospital, Out- Patient Department ; Attend- 
ing Physician Northwestern Dispensary, New York. i2mo. 

Cloth, 2.00 

Leffmann's Compend of Chemistry. Inorganic and Organic. 
Including Urinary Analysis. Third Edition. Revised. 

Cloth, 1. 00; Interleaved for Notes, 1.25 

Leffmann and Beam. Progressive Exercises in Practical 
Chemistry. i2mo. Illustrated. Cloth, 1.00 

Muter. Practical and Analytical Chemistry. Fourth Edi- 
tion. Revised, to meet the requirements of American Medical 
Colleges, by Prof. C. C. Hamilton. Illustrated. Cloth, 2.00 

Holland. The Urine, Common Poisons, and Milk Analysis, 
Chemical and Microscopical. For Laboratory Use. Fourth 
Edition, Enlarged. Illustrated. Cloth, 1.00 

Van Niiys. Urine Analysis. Illus. Cloth, 2.00 

Wolff's Applied Medical Chemistry. By Lawrence Wolff, 
m.d., Dem. of Chemistry in Jefferson Medical College. Clo., 1.00 

CHILDREN. 

Goodhart and Starr. The Diseases of Children. Second 
Edition. By J. F. Goodhart, m.d., Physician to the Evelina 
Hospital for Children ; Assistant Physician to Guy's Hospital, 
London. Revised and Edited by Louis Starr, m.d., Clinical 
Professor of Diseases of Children in the Hospital of the Univer- 
sity of Pennsylvania; Physician to the Children's Hospital, 
Philadelphia. Containing many Prescriptions and Formulae, 
conforming to the U. S. Pharmacopoeia, Directions for making 
Artificial Human Milk, for the Artificial Digestion of Milk, etc. 
Illustrated. Cloth, 3.00; Leather, 3.50 

Hatfield. Diseases of Children. By M. P. Hatfield, m.d., 

Professor of Diseases of Children, Chicago Medical College. 

Colored Plate. i2mo. Cloth, 1. 00; Interleaved, 1.25 

49* See pages 14 and IS for list of ? Quiz-Compends? 



8 STUDENTS' TEXT-BOOKS AND MANUALS. 

Children; — Continued. 
Starr. Diseases of the Digestive Organs in Infancy and 
Childhood. With chapters on the Investigation of Disease, 
and on the General Management of Children. By Louis Starr, 
m.d., Clinical Professor of Diseases of Children in the Univer- 
sity of Pennsylvania. Illus. Second Edition. Cloth, 2.25 

DENTISTRY. 

Fillebrown. Operative Dentistry. 330 Illus. Cloth, 2.50 

Flagg's Plastics and Plastic Filling. 4th Ed. Cloth, 4.00 
Gorgas. Dental Medicine. A Manual of Materia Medica and 
Therapeutics. Fourth Edition. Cloth, 3.50 

Harris. Principles and Practice of Dentistry. Including 
Anatomy, Physiology, Pathology, Therapeutics, Dental Surgery 
and Mechanism. Twelfth Edition. Revised and enlarged by 
Professor Gorgas. 1028 Illustrations. Cloth, 7.00 ; Leather, 8.00 
Richardson's Mechanical Dentistry. Fifth Edition. 569 
Illustrations. 8vo. Cloth, 4.50; Leather, 5.50 

Sewill. Dental Surgery. 200 Illustrations. 3d Ed. Clo., 3.00 
Taft's Operative Dentistry. Dental Students and Practitioners. 
Fourth Edition. 100 Illustrations. Cloth, 4.25 ; Leather, 5.00 
Talbot. Irregularities of the Teeth, and their Treatment. 
Illustrated. 8vo. Second Edition. Cloth, 3.00 

Tomes' Dental Anatomy. Third Ed. 191 Illus. Cloth, 4.00 
Tomes' Dental Surgery. 3d Edition. Revised. 292 Illus. 
772 Pages. Cloth, 5.00 

Warren. Compend of Dental Pathology and Dental Medi- 
cine. Illustrated. Cloth, 1. 00; Interleaved, 1.25 

DICTIONARIES. 

Gould's New Medical Dictionary. Containing the Definition 
and Pronunciation of all words in Medicine, with many useful 
Tables etc. y 2 Dark Leather, 3.25 ; y 2 Mor., Thumb Index 4.25 

Harris' Dictionary of Dentistry. Fifth Edition. Completely 
revised and brought up to date by Prof. Gorgas. 

Cloth, 5.00; Leather, 6.00 

Cleaveland's Pronouncing Pocket Medical Lexicon. 31st 
Edition. Giving correct Pronunciation and Definition. Very 
small pocket size. Cloth, red edges .75 ; pocket-book style, 1.00 

Longley's Pocket Dictionary. The Student's Medical Lexicon, 
giving Definition and Pronunciation of all Terms used in Medi- 
cine, with an Appendix giving Poisons and Their Antidotes, 
Abbreviations used in Prescriptions, Metric Scale of Doses, etc. 
24mo. Cloth, 1. 00; pocket-book style, 1.25 

$^ See pages 2 to 5 for list of Students' Manuals, 



STUDENTS' TEXT-BOOKS AND MANUALS. 9 

EYE. 

Hartridge on Refraction. 5th Edition. Illus. Cloth, 2.00 

Hartridge on the Ophthalmoscope. Illustrated. Cloth, 1.50 
Meyer. Diseases of the Eye. A complete Manual for Stu- 
dents and Physicians. 270 Illustrations and two Colored Plates. 
8vo. Cloth, 4.50; Leather, 5.50 

Swanzy, Diseases of the Eye and their Treatment. 158 
Illustrations. Fourth Edition. Cloth, 3 00 

Fox and Gould. Compend of Diseases of the Eye and 
Refraction. 2d Ed. Enlarged. 71 Illus. 39 Formulae. 

Cloth, 1. 00 ; Interleaved for Notes, 1.25 

ELECTRICITY. 

Bigelow. Plain Talks on Medical Electricity and Batteries. 

Illustrated. With a Glossary of Electrical Terms. Cloth, 1.00 

Mason's Compend of Medical and Surgical Electricity. 

With numerous Illustrations. i2mo. Cloth, 1.00 

HYGIENE. 

Parkes' (Ed. A.) Practical Hygiene. Seventh Edition, en- 
larged. Illustrated. 8vo. Cloth, 4.50 

Parkes' (L. C.) Manual of Hygiene and Public Health. 
Second Edition. i2mo. Cloth, 2.50 

Wilson's Handbook of Hygiene and Sanitary Science. 
Seventh Edition. Revised and Illustrated. In Press. 

MATERIA MEDICA AND THERAPEUTICS. 

Potter's Compend of Materia Medica, Therapeutics and 
Prescription Writing. Fifth Edition, revised and improved. 
See Page if. Cloth, 1.00; Interleaved for Notes, 1.25 

Biddle's Materia Medica. Eleventh Edition. By the late 
John B. Biddle, m.d., Prof, of Materia Medica in Jefferson Col- 
lege, Philadelphia. Revised by Clement Biddle, m.d., and 
Henry Morris, m.d. 8vo., illustrated. Cloth, 4.25; Leather, 5.00 

Potter. Handbook of Materia Medica, Pharmacy and 
Therapeutics. Including Action of Medicines, Special Thera- 
peutics, Pharmacology, etc. By Saml. O. L. Potter, m.d., 
m.r.c.p. (Lond.), Professor of the Practice of Medicine in 
Cooper Medical College, San Francisco. Third Revised and 
Enlarged Edition. 8vo. Cloth, 4.00; Leather, 5.00 

Waring. Therapeutics. With an Index of Diseases and 
Remedies. 4th Edition. Revised. Cloth, 3.00; Leather, 3.50 
Xfc^* See pages 14 and 13 for list of ? Quiz- Compends ? 



10 STUDENTS' TEXT-BOOKS AND MANUALS. 

MEDICAL JURISPRUDENCE. 

Reese. A Text-book of Medical Jurisprudence and Toxi- 
cology. By John J. Reese, m.d., Professor of Medical Juris- 
prudence and Toxicology in the Medical Department of the 
University of Pennsylvania ; President of the Medical Juris- 
prudence Society of Philadelphia; Physician to St. Joseph's 
Hospital ; Corresponding Member of The New York Medico- 
legal Society. Third Edition. Cloth, 3.00; Leather, 3.50 

OBSTETRICS AND GYNECOLOGY. 

Davis. A Manual of Obstetrics. By Edw. P. Davis, Dem- 
onstrator of Obstetrics, Jefferson Medical College, Philadelphia. 
Colored Plates, and 130 other Illustrations. i2mo. Cloth, 2.00 

Byford. Diseases of Women. The Practice of Medicine and 
Surgery, as applied to the Diseases and Accidents Incident to 
Women. By W. H. Byford, a.m., m.d., Professor of Gynaecology 
in Rush Medical College and of Obstetrics in the Woman's Med- 
ical College, etc., and Henry T. Byford, m.d., Surgeon to the 
Woman's Hospital of Chicago. Fourth Edition. Revised and 
Enlarged. 306 Illustrations, over 100 of which are original. 
Octavo. 832 pages. Cloth, 5.00 ; Leather, 6.00 

Cazeaux and Tarnier's Midwifery. With Appendix, by 

Munde. The Theory and Practice of Obstetrics ; including the 
Diseases of Pregnancy and Parturition, Obstetrical Operations, 
etc. Eighth American, from the Eighth French and First 
Italian Edition. Edited by Robert J. Hess, m.d., Physician to 
the Northern Dispensary, Philadelphia, with an appendix by 
Paul F. Munde, m.d., Professor of Gynaecology at the N. Y. 
Polyclinic. Illustrated by Chromo-Lithographs, and other Full- 
page Plates, seven of which are beautifully colored, and numerous 
Wood Engravings. One Vol., 8vo. Cloth, 5.00; Leather, 6.00 

Lewers' Diseases of "Women. A Practical Text-Book. 139 
Illustrations. Second Edition. Cloth, 2.50 

Parvin's Winckel's Diseases of "Women. Second Edition. 

Including a Section on Diseases of the Bladder and Urethra. 
150 Illus. Revised. Seepages. Cloth, 3.00; Leather, 3.50 

Morris. Compend of Gynaecology. Illustrated. Cloth, 1.00 

WinckePs Obstetrics. A Text-book on Midwifery, includ- 
ing the Diseases of Childbed. By Dr. F. Winckel, Professor 
of Gynaecology, and Director of the Royal University Clinic for 
Women, in Munich. Authorized Translation, by J. Clifton 
Edgar, m.d., Lecturer on Obstetrics, University Medical Col- 
lege, New York, with nearly 200 handsome illustrations, the 
majority of which are original. 8vo. Cloth, 6.00; Leather, 7.00 

Landis' Compend of Obstetrics. Illustrated. 4th edition, 
enlarged. Cloth, 1.00; Interleaved for Notes, 1.25 

Galabin's Midwifery. By A. Lewis Galabin, m.d., f.r.c.p. 
227 Illustrations. Seepages. Cloth, 3.00; Leather, 3.50 

4®* See pages 2 to 5 for Hst of New Manuals. 



STUDENTS' TEXT-BOOKS AND MANUALS. 



PATHOLOGY. HISTOLOGY. BIOLOGY. 

Bowlby. Surgical Pathology and Morbid Anatomy, for 
Students. 135 Illustrations. i2mo. Cloth, 2.00 

Davis' Elementary Biology. Illustrated. Cloth, 4.00 

Gilliam's Essentials of Pathology. A Handbook for Students. 
47 Illustrations. i2mo. Cloth, 2.00 

*^e*The object of this book is to unfold to the beginner the funda- 
mentals of pathology in a plain, practical way, and by bringing 
them within easy comprehension to increase his interest in the study 
of the subject. 

Gibbes' Practical Histology and Pathology. Third Edition. 

Enlarged. i2mo. Cloth, 1.75 

Virchow's Post-Mortem Examinations. 3d Ed. Cloth, 1.00 

PHYSICAL DIAGNOSIS. 

Fenwick. Student's Guide to Physical Diagnosis. 7th 
Edition. 117 Illustrations. i2mo. Cloth, 2.25 

Tyson's Student's Handbook of Physical Diagnosis. Illus- 
trated. i2mo. Cloth, 1.25 

PHYSIOLOGY. 

Yeo's Physiology. Fifth Edition. The most Popular Stu- 
dents' Book. By Gerald F. Yeo, m.d., f.r.c.s., Professor of 
Physiology in King's College, London. Small Octavo. 758 
pages. 321 carefully printed Illustrations. With a Full 
Glossary and Index. See Page 3. Cloth, 3.00; Leather, 3.50 

Brubaker's Compend of Physiology. Illustrated. Sixth 
Edition. Cloth, 1.00; Interleaved for Notes, 1.25 

Stirling. Practical Physiology, including Chemical and Ex- 
perimental Physiology. 142 Illustrations. Cloth, 2.25 

Kirke's Physiology. New 12th Ed. Thoroughly Revised and 
Enlarged. 502 Illustrations. Cloth, 4.00; Leather, 5.00 

Landois ' Human Physiology. Including Histology and Micro- 
scopical Anatomy, and with special reference to Practical Medi- 
cine. Fourth Edition. Translated and Edited by Prof. Stirling. 
845 Illustrations. Cloth, 7.00; Leather, 8.00 

" With this Text-book at his command, no student could fail in 

his examination." — Lancet. 

Sanderson's Physiological Laboratory. Being Practical Ex- 
ercises for the Student. 350 Illustrations. 8vo. Cloth, 5.00 

PRACTICE. 

Taylor. Practice of Medicine. A Manual. By Frederick 
Taylor, m.d., Physician to, and Lecturer on Medicine at, Guy's 
Hospital, London ; Physician to Evelina Hospital for Sick Chil- 
dren, and Examiner in Materia Medica and Pharmaceutical 
Chemistry, University of London. Cloth, 4.00; Leather, 5.00 

4SJ* See pages 14 and IS for list of ? Quiz- Commends f 



12 STUDENTS' TEXT-BOOKS AND MANUALS. 

Practice : — Continued. 

Roberts' Practice. New Revised Edition. A Handbook 
of the Theory and Practice of Medicine. By Frederick T. 
Roberts, m.d. ; m.r.c.p., Professor of Clinical Medicine and 
Therapeutics in University College Hospital, London. Seventh 
Edition. Octavo. Cloth, 5.50 ; Sheep, 6.50 

Hughes. Compend of the Practice of Medicine. 4th Edi- 
tion. Two parts, each, Cloth, 1.00; Interleaved for Notes, 1.25 
Part i. — Continued, Eruptive and Periodical Fevers, Diseases 

of the Stomach, Intestines, Peritoneum, Biliary Passages, Liver, 

Kidneys, etc., and General Diseases, etc. 

Part ii. — Diseases of the Respiratory System, Circulatory 

System and Nervous System ; Diseases of the Blood, etc. 
Physicians' Edition. Fourth Edition. Including a Section 
on Skin Diseases. With Index. 1 vol. Full Morocco, Gilt, 2.50 

From John A. Robinson, M.D., Assistant to Chair of Clinical 
Medicine, now Lecturer on Materia Medica, Rush Medical Col- 
lege, Chicago. 
" Meets with my hearty approbation as a substitute for the 

ordinary note books almost universally used by medical students. 

It is concise, accurate, well arranged and lucid, . . . just the 

thing for students to use while studying physical diagnosis and the 

more practical departments of medicine." 

PRESCRIPTION BOOKS. 

Wythe's Dose and Symptom Book. Containing the Doses 
and Uses of all the principal Articles of the Materia Medica, etc. 
Seventeenth Edition. Completely Revised and Rewritten. Just 
Ready. 32010. Cloth, 1. 00; Pocket-book style, 1.25 

Pereira's Physician's Prescription Book. Containing Lists 
of Terms, Phrases, Contractions and Abbreviations used in 
Prescriptions Explanatory Notes, Grammatical Construction ot 
Prescriptions, etc., etc. By Professor Jonathan Pereira, m.d. 
Sixteenth Edition. 32mo. Cloth, 1. 00; Pocket-book style, 1.25 

PHARMACY. 

Stewart's Compend of Pharmacy. Based upon Remington's 
Text-Book of Pharmacy. Third Edition, Revised. With new 
Tables, Index, Etc. Cloth., 1.00 ; Interleaved for Notes, 1.25 

Robinson. Latin Grammar of Pharmacy and Medicine. 
By H. D. Robinson, ph.d., Professor of Latin Language and 
Literature, University of Kansas, Lawrence. With an Intro- 
duction by L. E. Sayre, ph.g., Professor of Pharmacy in, and 
Dean of, the Dept. of Pharmacy, University of Kansas. i2mo. 

Cloth, 2.00 

SKIN DISEASES. 

Anderson, (McCall) Skin Diseases. A complete Text-Book, 
with Colored Plates and numerous Wood Engravings. 8vo. 

Cloth, 4.50; Leather, 5.50 

Van Harlingen on Skin Diseases. A Handbook of the Dis- 
eases of the Skin, their Diagnosis and Treatment (arranged alpha- 
betically). By Arthur Van Harlingen, m.d., Clinical Lecturer 
on Dermatology, Jefferson Medical College ; Prof, of Diseases of 
the Skin in the Philadelphia Polyclinic. 2d Edition. Enlarged. 
With colored and other plates and illustrations. i2mo. Cloth, 2.50 
4®=* See pages 2 to 5 for list of New Manuals. 



STUDENTS' TEXT-BOOKS AND MANUALS. 13 

SURGERY AND BANDAGING. 

Moullin's Surgery, A new Text-Book. 500 Illustrations (some 
colored), 200 of which are original. 

Cloth, net 7.00; Leather, net 8.00 

Jacobson. Operations in Surgery. A Systematic Handbook 
for Physicians, Students and Hospital Surgeons. By W. H. A. 
Jacobson, b.a., Oxon. f.r.c.s. Eng. ; Ass't Surgeon Guy's Hos- 
pital ; Surgeon at Royal Hospital for Children and Women, etc. 
199 Illustrations. 1006 pages. 8vo. Cloth. 5.00; Leather, 6.00 

Heath's Minor Surgery, and Bandaging. Ninth Edition. 142 
Illustrations. 60 Formulae and Diet Lists. Cloth, 2.00 

Horwitz's Compend of Surgery, Minor Surgery and 
Bandaging, Amputations, Fractures, Dislocations, Surgical 
Diseases, and the Latest Antiseptic Rules, etc., with Differential 
Diagnosis and Treatment. By Orville Horwitz, b.s., m.d., 
Demonstrator of Surgery, Jefferson Medical College. 4th edition. 
Enlarged and Rearranged. 136 Illustrations and 84 Formulae. 
i2mo. Cloth, 1. 00 ; Interleaved for the addition of Notes, 1.25 
*** The new Section on Bandaging and Surgical Dressings, con- 
sists of 32 Pages and 41 Illustrations. Every Bandage of any 
importance is figured. This, with the Section on Ligation of 
Arteries, forms an ample Text-book for the Surgical Laboratory. 

Walsham. Manual of Practical Surgery. Third Edition. 
By Wm. J. Walsham, m.d., f.r.c.s., Asst. Surg, to, and Dem 
of Practical Surg, in, St. Bartholomew's Hospital; Surgeon to 
Metropolitan Free Hospital, London. With 318 Engravings. 
See Page 2. Cloth, 3.00; Leather, 3.50 

URINE, URINARY ORGANS, ETC. 

Holland. The Urine, and Common Poisons and The 
Milk. Chemical and Microscopical, for Laboratory Use. Illus- 
trated. Fourth Edition. i2mo. Interleaved. Cloth, 1.00 

Ralfe. Kidney Diseases and Urinary Derangements. 42 Illus- 
trations. i2mo. 572 pages. Cloth, 2.75 

Marshall and Smith. On the Urine. The Chemical Analysis of 
the Urine. By John Marshall, m.d., Chemical Laboratory, Univ. 
of Penna; and Prof. E. F. Smith, ph.d. Col. Plates. Cloth, 1.00 

Tyson. On the Urine. A Practical Guide to the Examination 
of Urine. With Colored Plates and Wood Engravings. 7th Ed. 
Enlarged. i2mo. Cloth, 1.50 

Van Niiys, Urine Analysis. Illus. Cloth, 2.00 

VENEREAL DISEASES. 

Hill and Cooper. Student's Manual of Venereal Diseases, 
with Formulae. Fourth Edition. i2mo. Cloth, 1.00 

4®=* See pages 14 and 75 for list of ? Quiz-Compends f 



NEW AND REVISED EDITIONS. 

PQUIZ-COMPENDS? 

The Best Compends for Students' Use 
in the Quiz Class, and when Pre- 
paring for Examinations. 

Compiled in accordance zuith the latest teachings of promi- 
nent lecturers and the most popular Text-books. 

They form a most complete, practical and exhaustive 
set of manuals, containing information nowhere else col- 
lected in such a condensed, practical shape. Thoroughly 
up to the times in every respect, containing many new 
prescriptions and formulae, and over two hundred and 
fifty illustrations, many of which have been drawn and 
engraved specially for this series. The authors have had 
large experience as quiz-masters and attaches of colleges, 
with exceptional opportunities for noting the most recent 
advances and methods. 

Cloth, each $1.00. Interleaved for Notes, $1.25. 
No. 1. HUMAN ANATOMY, "Based upon Gray." Fifth 
Enlarged Edition, including Visceral Anatomy, formerly 
published separately. 16 Lithograph Plates, New 
Tables and 117 other Illustrations. By Samuel O. L. 
Potter, m.a., m.d., m.r.c.p. (Lond.,) late A. A. Surgeon U. S. 
Army. Professor of Practice, Cooper Medical College, San Fran- 
cisco. 
Nos. 2 and 3. PRACTICE OF MEDICINE. Fourth Edi- 
tion. By Daniel E. Hughes, m.d., Demonstrator of Clinical 
Medicine in Jefferson Medical College, Philadelphia. In two parts. 
Part I. — Continued, Eruptive and Periodical Fevers, Diseases 
of the Stomach, Intestines, Peritoneum, Biliary Passages, Liver, 
Kidneys, etc. (including Tests for Urine), General Diseases, etc. 

Part II. — Diseases of the Respiratory System (including Phy- 
sical Diagnosis), Circulatory System and Nervous System; Dis- 
eases of the Blood, etc. 

*** These little books can be regarded as a full set of notes upon 
the Practice of Medicine, containing the Synonyms, Definitions, 
Causes, Symptoms, Prognosis, Diagnosis, Treatment, etc., of each 
disease, and including a number of prescriptions hitherto unpub- 
lished. 

No. 4. PHYSIOLOGY, including Embryology. Sixth 
Edition. By Albert P. Brubaker, m.d., Prof, of Physiology, 
Penn'a College of Dental Surgery ; Demonstrator of Physiology 
in Jefferson Medical College, Philadelphia. Revised, Enlarged, 
with new Illustrations. 

No. 5. OBSTETRICS. Illustrated. Fourth Edition. By 
Henry G. Landis, m.d.. Prof, of Obstetrics and Diseases of 
Women, in Starling Medical College, Columbus, O. Revised 
Edition. New Illustrations. 



BLAKISTON'S ? QUIZ-COMPENDS ? 

No. 6. MATERIA MEDICA, THERAPEUTICS AND 
PRESCRIPTION WRITING. Fifth Revised Edition. 

With especial Reference to the Physiological Action of Drugs, 
and a complete article on Prescription Writing. Based on the 
Last Revision of the U. S. Pharmacopoeia, and including many 
unofficinal remedies. By Samuel O. L. Potter, m.a., m.d., 
m.r.c.p. (Lond.,) late A. A. Surg. U. S. Army; Prof, of Practice, 
Cooper Medical College, San Francisco. Improved and Enlarged, 
with Index. 

No. 7. GYNAECOLOGY. A Compend of Diseases of Women. 
By Henry Morris, m.d., Demonstrator of Obstetrics, Jefferson 
Medical College, Philadelphia. 45 Illustrations. 

No. 8. DISEASES OF THE EYE AND REFRACTION, 
including Treatment and Surgery. By L. Webster Fox, m.d., 
Chief Clinical Assistant Ophthalmological Dept., Jefferson Med- 
ical College, etc., and Geo. M. Gould, m.d. 71 Illustrations, 39 
Formulae. Second Enlarged and Improved Edition. Index. 

No. 9. SURGERY, Minor Surgery and Bandaging. Illus- 
trated. Fourth Edition. Including Fractures, Wounds, 
Dislocations, Sprains, Amputations and other operations ; Inflam- 
mation, Suppuration, Ulcers, Syphilis, Tumors, Shock, etc. 
Diseases of the Spine, Ear, Bladder, Testicles, Anus, and 
other Surgical Diseases. By Orville Horwitz, a.m., m.d., 
Demonstrator of Surgery, Jefferson Medical College. Revised 
and Enlarged. 84 Formulae and 136 Illustrations. 

No. 10. CHEMISTRY. Inorganic and Organic. For Medical 
and Dental Students. Including Urinary Analysis and Medical 
Chemistry. By Henry Leffmann, m.d., Prof, of Chemistry in 
Penn'a College of Dental Surgery, Phila. Third Edition, Revised 
and Rewritten, with Index. 

No. 11. PHARMACY. Based upon " Remington's Text-book 
of Pharmacy." By F. E. Stewart, m.d., ph. g., Quiz-Master 
at Philadelphia College of Pharmacy. Third Edition, Revised. 

No. 12. VETERINARY ANATOMY AND PHYSIOL- 
OGY. 29 Illustrations. By Wm. R. Ballou, m.d., Prof, of 
Equine Anatomy at N. Y. College of Veterinary Surgeons. 

No. 13. DENTAL PATHOLOGY AND DENTAL MEDI- 
CINE. Containing all the most noteworthy points of interest 
to the Dental student. By Geo. W. Warren, d.d.s., Clinical 
Chief, Penn'a College of Dental Surgery, Philadelphia. Illus. 

No. 14. DISEASES OF CHILDREN. By Dr. Marcus P. 
Hatfield, Prof, of Diseases of Children, Chicago Medical 
College. Colored Plate. 

Bound in Cloth, $1. Interleaved, for the Addition of Notes, $1.25. 



These books are constantly revised to keep up with 
the latest teachings and discoveries, so that they contain 
all the new methods and principles. No series of books 
are so complete in detail, concise in language, or so well 
printed and bound. Each one forms a complete set of 
notes upon the subject under consideration. 

Illustrated Descriptive Circular Free. 



JUST PUBLISHED. 



GOULD'S NEW 

Medical Dictionary 




compact. 

CONCISE. 

PRACTICAL. 

ACCURATE. 

COMPREHENSIVE 

UP TO DATE. 



It contains Tables of the Arteries, Bacilli, Gan- 
glia, Leucomaines, Micrococci, Muscles, 
Nerves, Plexuses, Ptomaines, etc., 
etc., that will be found of great 
use to the student. 



Small octavo, 520 pages, Half-Dark Leather, . $3.25 
With Thumb Index, Half Morocco, marbled edges, 4.25 

From J. M. DaCOSTA, M. D., Professor of Practice and 
Clinical Medicine, Jefferson Medical College, Philadelphia. 

"I find it an excellent work, doing credit to the learning and 
discrimination of the author** 

*** Sample Pages free. 



;;, 



